Compounds, compositions and methods for generating chemiluminescence with phosphatase enzymes

ABSTRACT

Novel heterocyclic compounds which generate chemiluminescence on reaction with a phosphatase enzyme are provided as well as a process for their preparation and intermediates useful therein. The compounds comprise a nitrogen, oxygen or sulfur-containing heterocyclic ring system bearing an exocyclic carbon—carbon double bond. The double bond is further substituted at the distal carbon with a phosphate group and an oxygen or sulfur atom-containing group. Novel compositions further comprising a cationic aromatic compound (CAC) in addition to the heterocyclic phosphate compound are provided. The addition of the CAC in the composition greatly increases the production of chemiluminescence and provides improved detection sensitivity. Compositions further comprising an anionic surfactant and a non-ionic surfactant provide additional improvements in detection sensitivity. The novel chemiluminescent compounds and compositions are useful in methods for producing light and in assays for phosphatase enzymes and enzyme inhibitors and in assays employing enzyme-labeled specific binding pairs.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a continuation of application Ser. No.09/539,816, filing date Mar. 31, 2000 now abandoned, which is adivisional application of Ser. No. 08/894,143, filing date Aug. 13, 1997now U.S. Pat. No. 6,045,727. The '143 application resulted from NationalStage Entry of PCT Application US97/00015 filed on Jan. 15, 1997. Thelatter PCT application is a continuation-in-part of U.S. applicationSer. No. 08/683,927, filed on Jul. 19, 1996, now abandoned and acontinuation-in-part of U.S. application Ser. No. 08/585,090, filed onJan. 16, 1996, now abandoned.

FIELD OF THE INVENTION

The present invention relates to chemiluminescent compounds which reactwith phosphatase enzymes to generate light. In particular, the presentinvention relates to chemiluminescent compounds containing aheterocyclic ring group and an enol phosphate group which react withoxygen upon removal of a phosphate group with a phosphatase enzyme toproduce an enolate which reacts with to produce chemiluminescence and acarbonyl compound.

The present invention further relates to compositions for generatingchemiluminescence by reaction with a phosphatase enzyme.Chemiluminescent compositions comprise a first compound containing aheterocyclic ring group and an enol phosphate group and a secondcompound which acts to increase light production from the reaction ofthe phosphate compound with a phosphatase enzyme. The present inventionrelates to methods for generating light or chemiluminescence by thereaction of a phosphatase enzyme with a chemiluminescent composition. Inparticular, the present invention relates to improvements in suchmethods which substantially increase light emission.

The invention further relates to the use of the chemiluminescentreactions and compositions in assay methods for detecting phosphataseenzymes and for detecting phosphatase-labeled specific binding partnersin immunoassays, nucleic acid probe assays and the like.

The present invention relates to a process for the preparation ofchemiluminescent compounds which react with phosphatase enzymes togenerate chemiluminescence. The present invention relates to novelintermediates useful in this process. In particular, the presentinvention relates to a process and intermediates for preparingchemiluminescent compounds containing a heterocyclic ring group and anenol phosphate group which react with oxygen upon removal of a phosphateprotecting group to produce chemiluminescence and a carbonyl compound.

BACKGROUND OF THE INVENTION

a. Chemiluminescent Detection of Phosphatase Enzymes.

Hydrolytic enzymes such as alkaline phosphatase are frequently used asmarkers or labels in enzyme-linked assays for biological molecules andother analytes of interest such as drugs, hormones, steroids and cancermarkers. In addition, phosphatase enzymes, e.g. alkaline phosphatase(AP) and acid phosphatase (AcP), are clinically significant in their ownright in human and veterinary diagnostics. Chemiluminescent detection ofthese enzymes offers a safe, convenient and sensitive means to provide aquantitative measure of the amount of enzyme in a sample or of theamount of an enzyme-labeled analyte or labeled specific binding partnerfor an analyte. Numerous chemiluminescent reaction schemes have beendeveloped to quantitate the level of particular hydrolytic enzymes. Mostof these schemes are complex and expensive, requiring multiple enzymesor several reagents. Commercial acceptance of most of such methods forlarge volume testing has been slow.

Applicant's co-pending U.S. patent application Ser. No. 08/585,090 whichis fully incorporated herein by reference, discloses thechemiluminescent reaction of certain heterocyclic compounds bearing anenol phosphate group with a phosphatase enzyme. Light emission isenhanced in the presence of cationic surfactants allowing thephosphatase to be detected at levels of 10⁻¹⁸ to 10⁻¹⁹ mol.

Applicant's co-pending U.S. patent application Ser. No. 08/683,927 whichis fully incorporated herein by reference, discloses the use of cationicaromatic compounds (CAC's) in conjunction with the chemiluminescentreaction of certain heterocyclic compounds bearing an enol phosphategroup with a phosphatase enzyme to substantially increase the amount oflight emitted. The detection limit of phosphatase enzymes is therebydramatically lowered.

b. Chemically and Enzymatically Triggerable Dioxetanes. Stable1,2-dioxetanes bearing a protected phenol group triggering group undergoa chemiluminescent decomposition upon removal of a protecting group (A.P. Schaap, T. S. Chen, R. S. Handley, R. DeSilva, and B. P. Giri,Tetrahedron Lett., 1155 (1987); A. P. Schaap, R. S. Handley, and B. P.Giri, Tetrahedron Lett., 935 (1987); A. P. Schaap, M. D. Sandison, andR. S. Handley, Tetrahedron Lett., 1159 (1987); and A. P. Schaap,Photochem. Photobiol., 47S, 50S (1988)). Enzymatically triggerabledioxetanes bear an aryloxide substituent which is blocked by anenzymatically removable protecting group. Reaction with a hydrolyticenzyme in an aqueous buffer reveals an aryloxide anion which acceleratesthe chemiluminescent decomposition rate of the dioxetane by orders ofmagnitude. Chemically triggerable dioxetanes bear an aryloxidesubstituent which is blocked by a protecting group which is removed by asimple chemical agent. An example is deprotection of an acetoxydioxetane with hydroxide or a silyloxy dioxetane with fluoride. Numerousexamples of such triggerable dioxetanes are disclosed, for example, inU.S. Pat. Nos. 4,857,652, 5,068,339, 4,952,707, 5,112,960, 5,220,005,5,326,882 and in PCT applications WO96/24849, WO94/10258 and WO94/26726.However, an inherent disadvantage of some triggerable dioxetanes istheir tendency to generate background chemiluminescence in the absenceof enzyme through slow thermal decomposition or non-enzymatichydrolysis.

c. Luminol Derivatives. A phosphate and a NAG derivative of luminol areknown (K. Sasamoto, Y. Ohkura, Chem. Pharm. Bull., 38, 1323-5 (1991); M.Nakazono, H. Nohta, K. Sasamoto, Y. Ohkura, Anal. Sci., 8, 779-83(1992)). Treatment of the luminol derivative with the appropriate enzymeliberates luminol which is reacted in a subsequent step withferricyanide to produce light.

d. Luciferin Derivatives. Phosphate and galactoside derivatives offirefly luciferin are known (N. Ugarova, Y. Vosny, G. Kutuzova, I.Dementieva, Biolum. and Chemilum. New Perspectives, P. Stanley and L. J.Kricka, eds., Wiley, Chichester, 511-4 (1981); W. Miska, R. Geiger, J.Biolumin. Chemilumin., 4, 119-28 (1989)). Treatment of the fireflyluciferin derivative with the appropriate enzyme liberates fireflyluciferin which is reacted in a second step with luciferase and ATP toproduce light.

e. Reactions Involving the Generation of Reducing Agents.Chemiluminescent methods involving the generation of a reducing agentfrom a phosphate ester catalyzed by alkaline phosphatase have beenreported. (M. Maeda, A. Tsuji, K. H. Yang, S. Kamada, Biolum. andChemilum. Current Status, 119-22 (1991); M. Kitamura, M. Maeda, A.Tsuji, J. Biolumin. Chemilumin., 10, 1-7 (1995); H. Sasamoto, M. Maeda,A. Tsuji, Anal. Chim. Acta, 306, 161-6 (1995)).The reducing agent causesa reaction between oxygen and lucigenin to produce light arising fromthe lucigenin. Representative reducing agents include ascorbic acid,glycerol, NADH, dihydroxyacetone, cortisol and phenacyl alcohol. Thesemethods are distinguished from the present invention which involves theproduction of light from the deprotected fluorescent compound, not fromlucigenin. The known methods of enzymatically generating a reducingagent for reaction with lucigenin all require a separate preliminaryincubation step between the enzyme and the phosphate compound. This addsadditional complexity and assay time.

U.S. Pat. No. 5,589,328 to Mahant discloses a chemiluminescent reactionwhereby indoxyl esters, thioindoxyl esters and benzofuran esters arehydrolyzed by an enzyme and thereby generate superoxide. Luminescence isamplified by adding a chemiluminescence generating reagent such aslucigenin. Lucigenin produces chemiluminescence by reaction withsuperoxide.

f. Cooled Enzyme Methods. Numerous other chemiluminescent methods andassays for determining hydrolytic enzymes such as phosphatase enzymesthrough coupled enzyme reactions are known. A compilation of suchmethods is listed in A. Tsuji, M. Maeda, H. Arakawa, Anal. Sci., 5,497-506 (1989). Other examples of dual enzyme chemiluminescent reactionsare described in U.S. Pat. No. 5,306,621 and commonly assignedapplication Ser. No. 08/300,367. The former describes the enzymaticgeneration of a peroxidase enhancer to enhance the chemiluminescentoxidation of luminol with a peroxidase; the latter describes theenzymatic generation of a peroxidase enhancer to enhance thechemiluminescent oxidation of an acridancarboxylic acid derivative witha peroxidase.

With the exception of enzyme-triggered dioxetanes, each of theaforementioned methods suffers the drawback of requiring multiplereagents or enzymes in order to generate the luminescent signal. Theadded expense or operational complexity has hindered commercialacceptance of these methods in spite of their demonstrated exceptionaldetection sensitivity. Chemiluminescent methods for detecting andquantitating hydrolytic enzymes which achieve these levels ofsensitivity but do not require additional enzymes or auxiliary reagentsin addition to the enzyme substrate would be advantageous. The presentinvention provides such methods and compounds.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide compounds forchemiluminescent detection of phosphatase enzymes which are thermallyand hydrolytically stable at room temperature over an extended period oftime and are cleaved by a phosphatase enzyme to cleave the phosphatemoiety.

It is also an object of the present invention to provide novel compoundssubstituted at one terminus of the double bond with a nitrogen, oxygenor sulfur-containing heterocyclic ring group and further substituted atthe other terminus of the double bond with an enzymatically cleavablephosphate (O—PO₃ ²⁻) group which can be triggered to decompose with thegeneration of light.

It is a further object of the present invention to provide a method andcompositions for generating chemiluminescence containing such novelcompounds which can be triggered by a phosphatase enzyme.

It is yet another object of the present invention to provide compoundswhich have superior light-generating ability and provide significantadvantages when used for the detection of phosphatase enzymes, and foruse in immunoassays and the detection of enzyme-linked nucleic acids,antibodies, haptens and antigens by generally known methods which employphosphatase labels for detection of analytes.

The above and other objects and advantages in accordance with thepresent invention are attained by a compound having the formula I:

wherein Het is a heterocyclic ring system comprising at least one fiveor six-membered ring which comprises at least one heteroatom selectedfrom N, O and S atoms, wherein Z is selected from the group consistingof O and S atoms, wherein R₆ is an organic group and wherein each M isindependently selected from H and a cationic center and wherein n is anumber which satisfies electroneutrality.

The above and other objects and advantages in accordance with thepresent invention are further attained by a reagent composition whichproduces chemiluminescence in the presence of a phosphatase enzyme whichcomprises in an aqueous solution: a compound of formula I and at leastone surfactant enhancer in an amount effective to enhance thechemiluminescence.

The above and other objects and advantages in accordance with thepresent invention are further attained by a method for producingchemiluminescence which comprises reacting a phosphatase enzyme with atleast one compound of formula I.

The above and other objects and advantages in accordance with thepresent invention are further attained by a method for detecting ananalyte in a sample by a chemiluminescent assay procedure whichcomprises: reacting a phosphatase enzyme with at least one compound offormula I to produce chemiluminescence for detecting the analyte;detecting the chemiluminescence; and relating the amount of thechemiluminescence to the amount of the analyte.

The above and other objects and advantages in accordance with thepresent invention are further attained by a method of detecting ananalyte in an assay procedure by a chemiluminescent reaction whichcomprises: providing a reagent composition which generateschemiluminescence in the presence of a phosphatase enzyme whichcomprises, in an aqueous solution, at least one compound of formula Iwhich reacts with the phosphatase enzyme wherein in the compound offormula I, and a surfactant enhancer in an amount effective to enhancethe chemiluminescence; reacting a phosphatase enzyme with thecomposition to produce chemiluminescence for detecting the analyte; andrelating the amount of chemiluminescence to the amount of the analyte.

It is also an object of the present invention to provide compositionscomprising a cationic aromatic compound and a compound of formula Iwhich can be triggered to decompose with the generation of light.

It is a further object of the present invention to provide an improvedmethod for generating chemiluminescence by reaction of a reagentcomposition with a phosphatase enzyme.

Still further, it is an object of the present invention to provide acomposition and method which rapidly produces efficientchemiluminescence on reaction with a phosphatase enzyme.

The above and other objects and advantages in accordance with thepresent invention are attained by a reagent composition comprising acationic aromatic compound and a compound of formula I.

The above and other objects and advantages in accordance with thepresent invention are further attained by a reagent composition whichproduces chemiluminescence in the presence of a phosphatase enzyme whichcomprises in an aqueous solution: a cationic aromatic compound, acompound of formula I which reacts with the phosphatase enzyme and, incombination, at least one anionic surfactant and at least one non-ionicsurfactant in amounts effective to provide rapid generation of efficientchemiluminescence.

It is a further object of the present invention to provide a syntheticprocess and intermediates useful therein for the preparation ofchemiluminescent compounds which react with phosphatase enzymes togenerate light.

It is a further object of the present invention to provide a process andintermediates for preparing chemiluminescent compounds of formula Icontaining a heterocyclic ring group and an enol phosphate group whichreacts with oxygen upon removal of a phosphate protecting group toproduce light and a carbonyl compound.

It is a further object of the present invention to provide a processcomprising phosphorylating an enolate of an ester or thioester compoundto produce a phosphodiester or triester intermediate compound which isdeprotected to a phosphate monoester salt.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing the time profile of the chemiluminescenceintensity emitted by 100 μL of a reagent consisting of a 0.33 mMsolution of acridan phosphate 1(9-(phenoxyphosphoryloxymethylidene)-10-methylacridan, disodium salt) in0.1 M tris buffer, pH 8.5 and 0.01 mg/mL of the enhancerpolyvinylbenzyltributylphosphonium chlorideco-polyvinylbenzyltrioctylphosphonium chloride (containing about a 3:1ratio of tributyl: trioctyl groups), (Enhancer A) triggered at 25° C. byaddition of 8×10⁻¹⁶ mol of alkaline phosphatase (AP). The figure alsoshows for comparison the chemiluminescence profile of the ester phenyl10-methylacridan-9-carboxylate in a similar reagent compositioncontaining the ester in place of 1.

FIG. 2 is a plot of the ultraviolet-visible absorption spectrum of areaction mixture containing 3 mL of a reagent composition containing 1with 2.4×10¹² mol of AP at room temperature. Curves labeled A-Frepresent scans taken 0, 5, 10, 20, 40 and 60 min after addition ofenzyme.

FIG. 3 is a plot of the chemiluminescence spectrum produced by reactionof 200 μL of a reagent composition containing 1 with 8×10⁻¹³ mol of APat room temperature.

FIG. 4 is a graph relating the amount of AP to the maximumchemiluminescence intensity emitted by 100 μL of a reagent containingacridan phosphate 1 triggered at room temperature. Chemiluminescenceemission was initiated at room temperature by addition of 10 μL ofsolutions of AP containing between 8×10⁻¹⁵ mol and 8×10⁻²⁰ of enzyme to100 μL of a 0.33 mM solution of acridan phosphate 1 in tris buffer, 0.1M (pH 8.5) containing 0.88 mM Mg⁺² and 0.01 mg/mL of Enhancer A in thewells of a white microplate. The term S-B refers to thechemiluminescence signal (S) in Relative Light Units (RLU) in thepresence of AP corrected for background chemiluminescence (B) in theabsence of AP. The graph shows linear detection of alkaline phosphatase.The calculated detection limit (twice the standard deviation of thebackground) was determined to be 8×10⁻¹⁹ mol under these conditions.

FIG. 5 is a graph relating the amount of AP to the totalchemiluminescence intensity emitted by 100 μL of a reagent compositioncomprising 0.33 mm acridan phosphate 1 in 0.1 M tris buffer, pH 9, 0.88mM MgCl₂. The composition was reacted with 10 μL of solutions of APcontaining between 8×10⁻¹⁵ and 8×10⁻²⁰ mol of enzyme or 10 μL of wateras a reagent blank for 4 min at ambient temperature in the wells of ablack microplate. A solution containing 0.5 mg/mL of Enhancer A in 1 NNaOH (100 μL) was injected and light intensity integrated for 10 sec.The graph shows linear detection of alkaline phosphatase.

FIG. 6 is a digitally scanned image of an x-ray film from a Western blotexperiment detecting human transferrin via an AP-labeled antibody on aPVDF membrane with a chemiluminescent reagent composition. Dilutions oftransferrin containing from 5000, 1000, 180, 30 and 5 pg, respectively,of protein were electrophoresed and transferred to the membrane. Proteinwas detected by briefly soaking the blot with a reagent compositioncontaining 0.5 mg/mL of Enhancer A in 0.2 M 2-amino-2-methyl-l-propanolbuffer, pH 9.6 containing 0.88 mM MgCl₂ and 0.66 mM acridan phosphate 1and exposing to x-ray film for 1 min after a 10 min incubation time.

FIG. 7 is a graph showing the effect on chemiluminescence productionfrom reaction of 5 with alkaline phosphatase (AP) by adding lucigenin tothe reaction solution. Equal volumes of two solutions containing 5 inbuffer were reacted with 8×10⁻¹⁶ moles of alkaline phosphatase (AP). Onesolution also contained 6.4 μM lucigenin.

FIG. 8 is a graph showing the time profile of the chemiluminescenceintensity emitted by 100 μL of Reagent A consisting of 0.1 M trisbuffer, pH 8,8, 6.4 μM lucigenin, 0.66 mM acridan phosphate 5 (from a1:100 dilution of a 0.066 M methanol solution), 1 mg/mL sodium dodecylsulfate, 0.01 mg/mL Na₂SO₃, 0.033% (w/v) TWEEN 20 and 0.88 mM MgCl₂triggered at room temperature by addition of 8×10⁻¹⁶ mol of AP. Thefigure also shows for comparison the chemiluminescence profile from areagent composition containing 5 and a cationic polymeric surfactantenhancer (0.25 TB/TO).

FIG. 9 is a graph relating the amount of AP to the maximumchemiluminescence intensity emitted by 100 μL of a reagent compositionof the present invention (reagent A) containing acridan phosphate 5,lucigenin, SDS and TWEEN 20 triggered at 25° C. For comparison, asimilar graph is presented from a set of experiments using a reagentcomposition (reagent B) containing the same acridan phosphate and(0.25TB/TO) but without lucigenin triggered at 37° C. Chemiluminescenceemission was initiated by addition of 10 μL of solutions of APcontaining between 8×10⁻¹³ and 8×10⁻²² mol of enzyme to 100 μL of therespective reagent compositions in the wells of a white microplate. Theterm S-B refers to the chemiluminescence signal (S) in Relative LightUnits (RLU) in the presence of AP corrected for backgroundchemiluminescence (B) in the absence of AP. The graph shows that reagentA including lucigenin achieves a 100-fold lower detection limit for AP.

FIG. 10 is a graph relating the amount of AP to the maximumchemiluminescence intensity emitted by 100 μL of a reagent compositioncomprising 0.66 mM acridan phosphate 7 in 0.1 M tris buffer, pH 8,8, 6.4μM lucigenin, 1 mg/mL sodium dodecyl sulfate, 0.01 mg/mL Na₂SO₃, 0.033%(w/v) TWEEN 20 and 0.88 mM MgCl₂. The composition was reacted with 10 μLof solutions of AP containing between 8×10⁻¹⁵ and 8×10⁻²² mol of enzymeor 10 μL of water as a reagent blank and measured after 75 sec atambient temperature in the wells of a black microplate.

FIG. 11 is a graph relating the amount of AP to the maximumchemiluminescence intensity emitted by 100 μL of a reagent compositioncomprising 0.66 mM acridan phosphate 8 in 0.1 M tris buffer, pH 8,8, 6.4μM lucigenin, 1 mg/mL sodium dodecyl sulfate, 0.01 mg/mL N₂SO₃, 0.033%(w/v) TWEEN 20 and 0.88 mM MgCl₂. The composition was reacted with 10 μLof solutions of AP containing between 8×10⁻¹⁵ and 8×10⁻²² mol of enzymeor 10 μL of water as a reagent blank and measured after 75 sec atambient temperature in the wells of a black microplate.

FIG. 12 is a graph showing the rapid generation of chemiluminescenceemitted by 100 μL of a reagent consisting of 0.1 M tris buffer, pH 8,8,6.4 μM lucigenin, 0.66 mm acridan phosphate 7 (from a 1:100 dilution ofa 0.066 M methanol solution), 1 mg/mL sodium dodecyl sulfate, 0.01 mg/mLNa₂SO₃, 0.033% (w/v) TWEEN 20 and 0.88 mM MgCl₂ triggered at roomtemperature by addition of 8×10⁻¹⁶ mol of AP.

FIG. 13 is a graph showing the results of a chemiluminescent immunoassayfor human chorionic gonadotropin using a detection reagent of theinvention.

FIG. 14 is a graph showing the results of a rapid chemiluminescentimmunoassay for thyroid stimulating hormone using a detection reagent ofthe invention.

FIG. 15 is a graph showing the results of a chemiluminescent immunoassayfor thyroid stimulating hormone using a detection reagent of theinvention.

FIG. 16 is a graph showing the results of a chemiluminescent immunoassayfor estradiol using a detection reagent of the invention.

FIG. 17 is a plot demonstrating the ability to simultaneously detectacid phosphatase and alkaline phosphatase in one sample. The upper traceis the light emitted from a sample containing both enzymes, the lowertrace is the light emitted from a sample containing only acidphosphatase and the middle trace represents the difference attributableto alkaline phosphatase.

FIG. 18 is a graph relating the amount of AP to the maximumchemiluminescence intensity emitted by 100 μL of a reagent compositioncomprising 0.66 mM acridan phosphate 12 in 0.1 M tris buffer, pH 8,8,6.4 μM lucigenin, 1 mg/mL sodium dodecyl sulfate, 0.01 mg/mL Na₂SO₃,0.033% (w/v) TWEEN 20 and 10 μM MgCl₂. The composition was reacted with10 μL of solutions of AP containing between 8×10⁻¹⁵ and 8×10⁻²² mol ofenzyme or 10 μL of water as a reagent blank and measured after 75 sec atambient temperature in the wells of a black microplate.

FIG. 19 is a graph relating the amount of AP to the maximumchemiluminescence intensity emitted by 100 μL of a reagent compositioncomprising 0.33 mM acridan phosphate 13 in 0.1 M tris buffer, pH 8,8,3.2 μM lucigenin, 0.5 mg/mL sodium dodecyl sulfate, 0.005 mg/mL Na₂SO₃,0.016% (w/v) TWEEN 20 and 5 μM MgCl₂. The composition was reacted with10 μL of solutions of AP containing between 8×10⁻¹⁵ and 8×10⁻²² mol ofenzyme or 10 μL of water as a reagent blank and measured after 75 sec atambient temperature in the wells of a black microplate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

It has been unexpectedly discovered as disclosed in Applicant'sco-pending U.S. patent application Ser. No. 08/585,090 that certainnovel compounds react with a phosphatase enzyme to generate easilydetectable chemiluminescence. Compounds of the present invention whichproduce chemiluminescence in the presence of a phosphatase enzyme havethe formula:

wherein Het is a heterocyclic ring system comprising at least one fiveor six-membered ring which comprises at least one heteroatom selectedfrom N, O and S atoms, wherein Z is an O or S atom, wherein R₆ is anorganic group which allows the light to be produced and wherein each Mis independently selected from H and a cationic center and wherein n isa number which satisfies electroneutrality. Reaction of the phosphatasewith I in the presence of oxygen leads to formation of acarbonyl-containing compound VI in an electronically excited state (VI*)and the dephosphorylated product VII. Radiative decay of VI* leads tolight emission.

The heterocyclic ring system of I contains at least one heteroatomselected from N, O and S atoms and is in conjugation with the ringcarbon bearing the exocyclic double bond. Preferred heterocycliccompounds include compounds of formulas II and III as depicted below andtheir double bond isomers or mixtures of the isomers.

where Z, M, n and R₆ are as defined above and R₁-R₅ are defined below.

Referring back to formula I, exemplary ring structures which cancomprise the group Het include the structures below where the asteriskdenotes the position of the exocyclic double bond. Without explicitlyshowing all possible substitution patterns, it is to be understood thateach ring position can contain substituents other than hydrogen. Otherheterocyclic ring compounds not specifically listed below but stillfalling within the scope of formula I will occur to the skilled artisan.

In all of the above compounds, the group R₁ is an organic groupcontaining from 1 to 50 atoms selected from C, N, O, S, P and halogenatoms exclusive of the necessary number of H atoms required satisfy thevalencies of the atoms in the group. The organic group is preferablyselected from the group consisting of alkyl, substituted alkyl, aryl,substituted aryl and aralkyl groups. More preferred groups for R₁include C₁-C₄ alkyl groups and benzyl groups.

In all of the above compounds, the groups R₂-R₅, which can be the sameor different, each are H or a substituent group which permits the lightto be produced and will generally contain from 1 to 50 atoms selectedfrom C, N, O, S, P and halogen atoms. Representative substituent groupswhich can be present include, without limitation, alkyl, substitutedalkyl, aryl, substituted aryl, aralkyl, alkenyl, alkynyl, alkoxy,aryloxy, halogen, amino, substituted amino groups, carboxyl,carboalkoxy, carboxamide, cyano, and sulfonate groups. Either or bothpairs of adjacent groups, i.e. R₂-R₃ or R₄-R₅, can be joined together asa carbocyclic or heterocyclic ring system comprising at least one 5 or6-membered ring which is fused to the ring bearing the exocyclic doublebond. Such fused heterocyclic rings can contain 1 or more N, O or Satoms and can be substituted at the ring carbons with groups other thanhydrogen such as those mentioned above.

Substituent groups can be incorporated in various quantities and atselected ring positions in order to modify the properties of thecompound or to provide for convenience of synthesis of the finalphosphate compound. Such properties include, for example,chemiluminescence quantum yield, rate of reaction with the enzyme,maximum intensity of light emission, duration of light emission,wavelength of light emission and solubility in the reaction medium.Specific substituents and their effects are illustrated in the specificexamples below, which, however, are not to be considered limiting thescope of the invention in any way.

Each of the groups M independently comprise a hydrogen atom or acationic center. A cationic center means a positively charged atom suchas a sodium atom Na⁺, a group of atoms such as an ammonium ion NH₄ ⁺ ora portion of a molecule with one or more sites of positive charge.Examples of the latter include dicationic compounds described in U.S.Pat. No. 5,451,347 to applicant and polymeric compounds with multiplecationic groups as described in applicant's U.S. Pat. No. 5,393,469. thepositive charge on a cationic center may take any unit value, i.e. 1, 2,3 etc. Exemplary cationic centers include, without limitation, alkalimetal ions, alkaline earth ions, quaternary ammonium ions and quaternaryphosphonium ions and are present in the number required by theirvalence. If two groups are required to be present in the compound offormula I for electroneutrality, they can be the same or different.Preferred counter ions are the alkali metal ions.

As noted above, the organic group R₆ can be any group which allows ordoes not interfere with the light production and preferably containsfrom 1 to 50 atoms selected from C, N, O, S, P and halogen atoms and thenecessary number of H atoms required satisfy the valencies of the atomsin the group. Groups which can function as the R₆group include, withoutlimitation, alkyl, substituted alkyl, aryl, substituted aryl and aralkylgroups. Substituent groups other than H atoms, such as ionic groups orpolar groups, can be incorporated in various numbers and at selectedpositions on the carbon chain or ring of R₆ in order to modify theproperties of the compound or to provide for convenience of synthesis ofthe final phosphate compound. Such properties include, for example,chemiluminescence quantum yield, rate of reaction with the enzyme,maximum intensity of light emission, duration of light emission,wavelength of light emission and solubility in the reaction medium.Specific substituents and their effects are illustrated in the specificexamples below, which, however, are not to be considered limiting thescope of the invention in any way.

A preferred class of compounds have the formula IV below wherein Ar isan aryl ring group containing at least one carbocyclic or heterocyclicaromatic ring and which can be further substituted, Z is selected from Oand S atoms, R₁ is as defined above, M is H or a monovalent or divalentcationic counter ion as defined above and n is 2 or 1, respectively.

The groups R₇ to R₁₄, which can be the same or different, each are H ora substituent group containing from 1 to 50 atoms selected from C, N, O,S, P and halogen atoms and which permit the light to be produced and caninclude, without limitation, alkyl, substituted alkyl, aryl, substitutedaryl, aralkyl, alkenyl, alkynyl, alkoxy, aryloxy, halogen, amino,substituted amino groups, carboxyl, carboalkoxy, carboxamide, cyano, andsulfonate groups. Adjacent groups, e.g. R₇-R₈ or R₈-R₉, can be joinedtogether as a carbocyclic or heterocyclic ring system comprising atleast one 5 or 6-membered ring. It is preferred that R₇ to R₁₄ areselected from hydrogen and alkoxy groups such as methoxy, ethoxy,t-butoxy and the like. Especially preferred compounds have the formula Vwhere Z is O or S and Ar is a phenyl group, a substituted phenyl group,a naphthyl group or a substituted naphthyl group and M and n are asdefined above.

Another aspect of the present invention is the use of compounds of anyof formulas I-V in a method to produce visible chemiluminescence byreaction with a phosphatase enzyme. Reaction of a compound of formulaI-V with a phosphatase enzyme in an aqueous buffer solution produceseasily detected chemiluminescence. Light intensity reaches a maximumlevel within minutes at room temperature when the reaction is conductedat alkaline pH. The reaction is conducted optionally in the presence ofan enhancer.

While not wishing to be bound by any specific mechanistic explanationfor this discovery at this point, molecular oxygen is a necessaryreactant and the reaction products are ketone VI, an ester or thioesterVII, a compound of the formula R₆ZH and phosphate ion. Light is emittedfrom the electronically excited state of VI. A necessary condition forthe production of light is that the reaction produces sufficient energyto form the excited state of VI. If VI is fluorescent thenchemiluminescence is produced directly from the reaction via emissionfrom the excited state of VI. An especially surprising finding is thatreaction of compounds of formula I with a phosphatase enzyme atmoderately basic pH produces far more intense light emission than isproduced by autoxidation of the enolate intermediate (the anion of VII)which would be expected to form upon cleavage of the phosphate group.

In a preferred method of producing chemiluminescence, a compoundcontaining an acridan ring is reacted with alkaline phosphatase in analkaline buffer with a pH between about 8 and 10 to produce a continuouschemiluminescence signal which commences upon reaction of the enzyme andthe phosphate compound. The light intensity at any time point can beincreased up to at least 40-fold by incorporation of at least onesurfactant enhancer as will be described in more detail below.

In a preferred method of producing light from the reaction of compoundIV with a phosphatase enzyme, the reaction is performed at a temperaturebetween 5° C. and 50° C., preferably between 20° C. and 40° C. in anaqueous buffer solution at a pH between 7 and 10.5, preferably between8.5 and 10. Compound IV is used at a concentration between 1 μM and 20mM, preferably between 10 μM and 1 mM. The enzyme is preferably analkaline phosphatase or an alkaline phosphatase conjugate. Light isemitted from the excited state of VIII.

Compounds of the present invention typically produce light over a100-200 nm wide band of emission, which exhibits a maximum intensity atwavelengths in the near ultraviolet to the visible region of theelectromagnetic spectrum. Typical wavelengths of maximum intensityλ_(max) in the range of 350-500 nm. It is contemplated that phosphatecompounds of formula I bearing a covalently linked fluorophore not inconjugation with the double bond of the vinyl phosphate moiety could,upon formation of the excited product VI*, undergo intramolecular energytransfer resulting in emission at longer wavelengths from the excitedstate of the fluorophore.

More than one compound of formula I can be used concurrently in a methodfor producing light by the action of a phosphatase enzyme. It may beadvantageous in some instances to simultaneously react two or morecompounds of formula I with the phosphatase enzyme. When the two or morecompounds have differing luminescent or physical properties, thecombination of the two may be desirable to produce a light emittingreaction with characteristics not readily achievable through the use ofany one compound. Examples of luminescent and physical properties whichcan differ between compounds I include emission spectrum, duration oflight emission, enzyme turnover, rate of rise of emission to maximum,hydrophobicity/hydrophilicity and solubility. While particularluminescent properties can differ among the compounds of formula I inthe present methods, the variation in properties does not detract fromthe basic utility of the compounds; selection of particular compoundswith desirable properties can be made by virtue of the teachings andmethods described herein.

Light emitted by the present method can be detected by any suitableknown means such as a luminometer, x-ray film, high speed photographicfilm, a CCD camera, a scintillation counter, a chemical actinometer orvisually. Each detection means has a different spectral sensitivity. Thehuman eye is optimally sensitive to green light, CCD cameras displaymaximum sensitivity to red light, x-ray films with maximum response toeither UV to blue light or green light are available. Choice of thedetection device will be governed by the application and considerationsof cost, convenience, and whether creation of a permanent record isrequired.

It is contemplated that fluorescent energy acceptors can be employed toshift the maximum emission to longer wavelengths (red-shifting). Varioustechniques for red-shifting emission are known in the art ofchemiluminescent reactions and assays. Covalently linked fluorophores asdescribed above are one example. Fluorescers can be added to thereaction solution as separate species. Fluorescers can be linked to anenhancer substance such as a cationic polymer or associated with anenhancer substance such as a micelle or polymer in order to bring thefluorescer in close contact to the compound. Alternately, the fluorescercan be provided in a non-fluorescent form which is convertible to thefluorescent form by removal of a phosphate group during the enzymereaction period. Examples of the latter type of compound includefluorescein diphosphate, coumarin phosphates such as4-methylumbelliferone phosphate, benzothiazole phosphates such asATTOPHOS (JBL Scientific, San Luis Obispo, Calif.).

At least one enhancer compound can also be employed in thechemiluminescent reaction of the present invention, in order to increasethe amount of light emitted. Enhancers which are effective in thepresent method can function by increasing the fraction of excited stateproduct molecules which emit light, by increasing the fraction ofproduct molecules which are formed in the excited state, by increasingthe rate of reaction or turnover of the enzyme, by increasing the rateof a subsequent chemical reaction step, by improving the stability ofthe enzyme, by promoting the association of the enzyme with the compoundof formula I, by inhibiting or preventing competitive non-luminescentside reactions or by any combination of these mechanisms. Enhancers willbe used in an amount effective to enhance the chemiluminescence,preferably between 0.001 and 5 mg/mL in the final reaction solution,more preferably between 0.01 and 2.5 mg/mL.

Enhancer compounds that are effective in the practice of the presentmethod are typically surfactant compounds, i.e. compounds which displaysurface active properties, e.g., surface tension depression, surfacewetting or detergency. Surfactants comprise a hydrophilic regioncontaining polar and/or ionic groups and a hydrophobic region containingmainly hydrocarbon groups or alkylenoxy groups or both. Surfactants arecategorized as cationic, anionic, nonionic and zwitterionic and can bemonomeric or polymeric. Cationic surfactant enhancers found useful inthe practice of the present invention include polyvinyl type polymerswith pendant quaternary phosphonium groups which are disclosed in U.S.Pat. No. 5,393,469 the disclosure of which is incorporated herein byreference. Exemplary polymers of this type includepolyvinylbenzyltributylphosphonium chloride copolymer withpolyvinylbenzyltrioctylphosphonium chloride and(polyvinylbenzyltributylphosphonium chloride). Polyvinyl type polymerswith pendant quaternary ammonium groups are also useful as enhancers inthe present invention. Examples of such polymers are disclosed in U.S.Pat. No. 5,112,960, the disclosure of which is incorporated herein byreference and include polyvinylbenzylbenzyldimethylammonium chloride andpolyvinylbenzyltributylammonium chloride.

Another category of cationic surfactant enhancers found useful in thepractice of the present invention are dicationic compounds bearing twoquaternary ammonium or phosphonium groups as disclosed in U.S. Pat. No.5,451,347 the disclosure of which is incorporated herein by reference.The compound(1-trioctylphosphoniummethyl-4-tributylphosphoniummethylbenzenedichloride) for example provides enhanced chemiluminescence when used ina method for producing light according to the present invention. Stillother cationic surfactant enhancers useful in the practice of thepresent invention are monoquaternary ammonium salts e.g.cetyltrimethylammonium chloride or bromide and monoquaternaryphosphonium salts such as cetyltrimethylammonium bromide.

Anionic surfactant enhancers include alkyl sulfates and alkylsulfonates.Nonionic surfactant enhancers include polyoxyethylenated alkylphenols,polyoxyethylenated alcohols, polyoxyethylenated ethers andpolyoxyethylenated sorbitol esters. Zwitterionic surfactant enhancersinclude quaternary ammoniumalkyl phosphates and sulfonates. Moreextensive lists of exemplary structures of each category of surfactantcan be found in any standard treatise on surfactants. Numerousrepresentative member surfactants have been tested and found to beeffective to varying degrees in increasing the amount or intensity oflight produced compared to the amount produced in its absence. Cationicsurfactants, in particular, quaternary ammonium and quaternaryphosphonium salts have been found to be among the most effectiveenhancers.

As described above, surfactant enhancers can also have fluorescentgroups covalently attached or associated through electrostatic orhydrophobic interactions.

In an alternate mode of performing the present chemiluminescentreactions, the chemiluminescent compound is reacted with a phosphataseenzyme in a buffer at a first pH in the range 5.0-9.5 for a first periodof time ranging from a few seconds to less than about 10 min in theabsence of an enhancer. Any light produced during this first period isneglected. Then a strongly basic trigger solution containing an enhanceris added at once and the burst of light measured either by measuring thepeak intensity, or integrating for a second fixed time period or untillight emission has ceased. It is desirable that the pH and amount ofenhancer be selected so that all of the light is emitted in a shortperiod of time, preferably about one minute or less. The pH of thetrigger solution should be >11 and preferably above 12. Preferred basesare sodium hydroxide and potassium hydroxide. Enhancers useful in thismode of reaction are as identified in the foregoing discussion and willbe used in an amount effective to enhance the chemiluminescence,preferably between 0.001 and 1 mg/mL in the final reaction solution.

This mode of generating the chemiluminescence may be advantageous inassays in which a large number of samples is processed simultaneouslyfor measurement at a later time. Detection of acid phosphatase can alsobe performed in this manner. An optional step which can also beincorporated into such a chemiluminescent reaction or assay is to add anenzyme inhibitor to the reaction system after the first period of timeto stop all further enzyme action.

Since the reaction is catalyzed by the phosphatase enzyme, exceedinglysmall quantities of the enzyme are sufficient to produce a detectableamount of light. Sensitivities of 1 attomol (1×10⁻¹⁸ mol) have beenachieved. The ability to detect such small amounts of phosphataseenzymes make the present chemiluminescent technology suitable foranalyses of many types of analytes using enzyme-linked assays.

The chemiluminescent reaction of the present invention provides aparticularly effective reagent for detection of AP conjugates onpolyvinylidene difluoride (PVDF) membranes, nylon membranes and onnitrocellulose filters and membranes. Surprisingly, it has been foundthat reaction of an antibody-AP conjugate on a PVDF membrane with areagent composition containing compound 1

provides an intense luminescence which rises to a maximum level nearlyinstantly and maintains essentially constant intensity for at least 2days. Detection on film and optimizing image intensity are thusparticularly convenient.

Surprisingly, it has been found that light emission produced on PVDFmembranes persists at useful levels for very long periods of time,exceeding a month. Art-known chemiluminescent reagents used inmembrane-based detection schemes provide a luminescent signal with atime course which shows either a rapid decay, e.g. luminol withperoxidase which decays within 3-4 hours, or a slow rise and gradualdecay as is the case with enzyme-triggered dioxetanes.

In another aspect, the present invention relates to a reagentcomposition for producing chemiluminescence by reaction with aphosphatase enzyme comprising an aqueous buffer with a pH between about7 and about 10.5, a compound of formula I at a concentration of 0.01-10mM and optionally at least one enhancer in an amount effective toenhance the chemiluminescence, preferably between 0.001 and 10 mg/mL.Formulations for chemiluminescent reaction with alkaline phosphatase canfurther comprise a magnesium or zinc salt at a concentration of 0.01-10mM for increasing the activity of the enzyme.

A preferred reagent composition for producing chemiluminescence byreaction with a phosphatase enzyme comprises an aqueous buffer with a pHbetween about 7 and about 10.5, acridan phosphate of formula IV or V ata concentration of 0.01-10 mM and a surfactant enhancer in an amounteffective to enhance the chemiluminescence, preferably between 0.001 and10 mg/mL. The formulation further comprises a magnesium salt at aconcentration of 0.01-10 mM.

It is preferred that the surfactant enhancer in the reagent compositionis selected from the group consisting of polymeric cationic enhancerscontaining ammonium or phosphonium groups and dicationic enhancerscontaining ammonium or phosphonium groups. Especially preferred arepolyvinyl polymers bearing a pendant trialkylphosphonium group on eachmonomeric unit and polyvinyl polymers bearing a pendant trialkylammoniumgroup or a benzyldialkylammonium group on each monomeric unit. Theamount and choice of enhancer can be selected for optimum performance ina given application as a matter of routine experimentation. A preferredcomposition for detection of AP or conjugates in solution comprises anamine buffer, pH 8.5 the compound9-(phenoxyphosphoryloxymethylidene)-10-methylacridan, disodium salt,0.1-1 mM, a magnesium salt, 0.1-1 mM, and Enhancer A(polyvinylbenzyltributyl-phosphonium chlorideco-polyvinylbenzyltrioctylphosphonium chloride containing about a 3:1ratio of tributyl: trioctyl groups), 0.01-0.1 mM. A preferredcomposition for detection of AP or conjugates on a membrane comprises anamine buffer, pH 9.6, the compound9-(phenoxyphosphoryloxymethylidene)-10-methylacridan, disodium salt,0.1-1 mm, a magnesium salt, 0.1-1 mM, and Enhancer A,0.1-1 mM.

Applicant's co-pending U.S. patent application Ser. No. 08/683,927discloses that adding a cationic aromatic compound (CAC) to the abovereaction system greatly increases the quantity and/or intensity of lightproduced. Further, adding the CAC to the compound of formula I in theabsence of the phosphatase enzyme does not lead to a correspondingincrease in spontaneous (background) chemiluminescence since it isbelieved that the CAC exerts its effect on a dephosphorylatedintermediate derived from compound I and not on compound I itself.Greatly increased sensitivity of detection of the phosphatase enzymeresults by virtue of the increased signal/background. It is significantthat light emission continues to arise from the excited state of VI andnot from the CAC.

A variety of CACs have been found to function to increase the quantityand/or intensity of light produced. CACs are aromatic compounds bearingat least one positive charge either on the aromatic ring or ring systemor residing on a substituent on one of the rings, provided that thesubstituent is in conjugation with the unsaturated ring atoms.

The CACs of the present invention are those compounds havingoxidation/reduction potentials suitable for causing an increase inchemiluminescence in reactions of the invention. The suitability ofcompounds as CACs can be readily determined by means of the methods setforth in the specific examples below. Without being bound by anyparticular mechanistic interpretation, it appears that an intermediateproduct of dephosphorylation of I undergoes a redox reaction which canbe reversible or irreversible. Molecular oxygen reacts with one or moreof the reacting species in the reaction selected from the CAC, a reducedform of the CAC or the dephosphorylated intermediate of compound I or anoxidized or reduced form thereof to ultimately form an oxygenatedreaction product derived from compound I. The oxygenated reactionproduct undergoes a chemiluminescent reaction, which is likely an O—Obond breaking reaction.

The CACs of the present invention can be a heteroaromatic ring compoundcomprising one or more isolated or fused aromatic rings containing atleast one atom other than carbon (heteroatom), preferably one or morenitrogen atoms in which the positive charge is substantially localizedon one or more of the heteroatoms. Examples of this class of CAC arecyanine dyes, thiacyanine dyes, carbocyanine dyes, thiacarbocyaninedyes, selenacarbocyanine dyes, azo dyes and acridinium derivatives ofthe formula:

wherein Q is an electron withdrawing group, X— is a non-interferinganionic counter ion and R is an alkyl or aralkyl group each of which canoptionally contain non-interfering substitutents. Acridinium derivativesin which some of the ring hydrogens are replaced by other substitutinggroups are also within the scope of functional CACs. The electronwithdrawing group Q can be e.g. a halogen atom such as Cl, a cyanogroup, or a carbonyl group such as an ester group —COOR, a thioestergroup —COSR, an amide group —CONR¹R² or a sulfonimide group—CON(R)SO₂R′. Similarly the CAC can be a derivative of aphenanthridinium or phenanthrolinium compound.

The CACs of the present invention can be an aromatic ring compoundcomprising one or more isolated or fused carbocyclic aromatic ringsbearing at least one cationic substituent containing at least oneheteroatom, provided that the cationic site is in conjugation with thearomatic ring. In the latter class of CAC it is preferred that theheteroatom be a nitrogen or sulfur atom. Examples include Methylene Blueand Nile Blue.

The CACs of the present invention can bear more than one positivecharge; e.g. dicationic compounds are within the scope of the invention.Exemplary compounds of this type include N,N′-dimethylbiacridiniumdinitrate, commonly known as lucigenin and1,1′-dimethyl-4,4′-bipyridinium dichloride, commonly known as methylviologen dichloride, or paraquat dichloride.

Additional compounds which are useful as the CAC component of thepresent invention include, by way of illustration, compounds in Table I.

Table 1. CACs

Alcian Yellow, Basic Blue 41, Basic Blue 66, Basic Red 29,

3-Benzyl-5-(2-hydroxyethyl)-4-methylthiazolium chloride,

[2-[2-[2-Chloro-3-[(1,3-dihydro-1,3,3-trimethyl-2H-indol-2-ylidene)ethylidene]-1-cyclohexen-1-yl]ethenyl]1,3,3-trimethylindoliumperchlorate, {IR-786 perchlorate},

trans-4-[4-(Dibutylamino)styryl]-1-methylpyridinium iodide,

5,5′-Dichloro-11-diphenylamino-3,3′-diethyl-10,12-ethylenethiatricarbocyanine perchlorate, {IR-140},

3,3′-Diethyl-9-methylthiacarbocyanine iodide,

1,1′-Diethyl-2,2′ quinotricarbocyanine iodide,

3,3′-Diethylselenacarbocyanine iodide,

3,3′-Diethylthiacyanine iodide,

3,3′-Diethylthiadicarbocyanine iodide,

2-[4-(Dimethylamino)styryl]-3-ethylbenzothiazolium iodide,

3,6-Dimethyl-2-(4-dimethylaminophenyl)-benzothiazolium bromide,

3,4-Dimethyl-5-(2-hydroxyethyl)thiazolium iodide,

4-[2-[3-[(2,6-Diphenyl-4H-thiopyran-4-ylidene)ethylidene]-2-phenyl-1-cyclo-hexen-1-yl]ethenyl]-2,6-diphenyl-thiopyryliumtetrafluoroborate {IR-1040},

5-[3-Ethoxy-4-(3-ethyl-5-methyl-2(3H)-benzothiazolylidene)-2-butenylidene]-3-ethyl-2-[(3-ethyl-4,5-diphenyl-2(3H)-thiazolylidene)methyl]-4,5-dihydro-4-oxothiazoliumiodide,

3-Ethyl-2-(2-hydroxy-1-propenyl)benzothiazolium chloride,

3-Ethyl-2-methylbenzothiazolium iodide,

3-Ethyl-2-methylbenzoxazolium iodide,

1-Ethyl-3-methyl-1H-imidazolium chloride,

Methylene Blue, Nile Blue A, and

Triphosphopyridine nucleotide, sodium salt hydrate

Another aspect of the present invention, therefore, is the use ofcompounds of any of formulas I-V and a CAC in a method to producedetectable chemiluminescence by reaction with a phosphatase enzyme.Reaction of a compound of formula I-V with a phosphatase enzyme in thepresence of a CAC in an aqueous buffer solution produces easily detectedchemiluminescence from the excited state of VI. Light intensity reachesa maximum level within seconds to minutes at room temperature when thereaction is conducted at alkaline pH.

In a preferred method of producing chemiluminescence, a compound offormula IV containing an acridan ring is reacted in the presence of aCAC with alkaline phosphatase in an alkaline buffer with a pH betweenabout 7 and 10.5 to produce a continuous chemiluminescence signal whichcommences upon reaction of the enzyme and rapidly reaches peakintensity. Further modifications and improvements in the light producingreaction can be realized by incorporation of an anionic surfactant and anon-ionic surfactant in combination as will be described in more detailbelow.

In a preferred method of producing light from the reaction of compoundIV with a phosphatase enzyme and a CAC, the reaction is performed at atemperature between 5° C. and 50° C., usually between 20° C. and 40° C.in an aqueous buffer solution at a pH between 7 and 10.5, preferablybetween about 8 and 10. It is particularly convenient to conduct thereaction at ambient temperature, without the need to precisely regulatethe temperature due to the relatively small influence of temperature onlight intensity near ambient temperature. Compound IV is used at aconcentration between 1 μM and 20 mM, preferably between 10 μM and 1 mM.The enzyme is preferably an alkaline phosphatase or an alkalinephosphatase conjugate.

More than one compound of formula I-V can be used concurrently in amethod for producing light by the action of a phosphatase enzyme in thepresence of a CAC. It can be advantageous in some instances tosimultaneously react two or more compounds of formula I-V with thephosphatase enzyme and the CAC. When the two or more compounds havediffering luminescent or physical properties, the combination of the twocan be desirable to produce a light emitting reaction withcharacteristics not readily achievable through the use of any onecompound. Examples of luminescent and physical properties which candiffer between compounds I-V include emission spectrum, duration oflight emission, enzyme turnover, rate of rise of emission to maximum,hydrophobicity/hydrophilicity and solubility.

Similarly, more than one CAC can be used concurrently in a method forproducing light by the action of a phosphatase enzyme. The CAC is usedat a concentration between 10⁻² M and 10⁻⁹ M, preferably between about10⁻⁴ M and 10⁻⁷ M. Desirable concentrations of a particular CAC for usein the present methods can be readily determined by means of the methodsset forth in the specific examples below

In another aspect, the present invention relates to a reagentcomposition for producing chemiluminescence by reaction with aphosphatase enzyme comprising an aqueous buffer with a pH between about7 and about 10.5, a compound of formula I-V and a CAC in an amounteffective to provide increased levels of chemiluminescence.

Additionally, it has been found that incorporation of certain additivesinto the reaction of a compound of formula I-V and a CAC with aphosphatase enzyme results in further desirable improvements in thelight producing reaction. Yet another aspect of the present inventiontherefore is a reagent composition comprising a compound of formula I-V,a CAC, an effective amount of an anionic surfactant and an effectiveamount of a non-ionic surfactant. Anionic surfactants serve tosubstantially increase the speed with which maximum chemiluminescenceintensity is reached. Non-ionic surfactants serve to substantiallyincrease the amount or intensity of chemiluminescence which isgenerated. Use of the latter compositions is particularly advantageousin providing increased light emission which rapidly reaches andmaintains peak light intensity.

In contrast to the methods of Applicant's co-pending application U.S.Ser. No. 08/585,090 in which cationic surfactants enhance the productionof chemiluminescence, the incorporation of cationic surfactants, bothmonomeric and polymeric, are ineffective in promoting thechemiluminescent reaction which requires the presence of a CAC. In somecases, inclusion of cationic surfactants virtually extinguishes lightproduction. The opposite effect of cationic surfactants in the presentmethods and compositions underscores the difference in thechemiluminescent reaction process which results from utilizing a CAC.

Anionic surfactants useful in compositions containing a CAC includealkyl sulfates and alkylsulfonates having an alkyl group of at least tencarbons. A preferred compound is sodium dodecyl sulfate (SDS). Anionicsurfactants are preferably used in an amount from about 10 mg/mL to 10μg/mL.

Non-ionic surfactants useful in compositions containing a CAC includepolyoxyethylenated alkylphenols, polyoxyethylenated alcohols,polyoxyethylenated ethers and polyoxyethylenated sorbitol esters.Preferred non-ionic surfactants include TWEEN 20 and TRITON X-100.Non-ionic surfactants are preferably used in an amount from about 1.0%to about 0.001% by weight of the composition.

More extensive lists of exemplary structures of each category ofsurfactant can be found in any standard treatise on surfactants and areknown to those of skill in the art. Numerous representative membersurfactants have been tested and found to be effective to varyingdegrees in increasing the amount or intensity of light produced comparedto the amount produced in its absence.

A still further aspect of the present invention is a reagent compositioncomprising a compound of formula I-V, a CAC, an effective amount of ananionic surfactant, an effective amount of a non-ionic surfactant and aneffective amount of a background reducing agent which reduceschemiluminescence produced by the composition in the absence of aphosphatase enzyme (background chemiluminescence).

Background reducing agents are compounds which reduce chemiluminescenceproduced by the composition in the absence of a phosphatase enzyme.These agents can also function by preventing the accumulation ofbackground chemiluminescence over a period of time. These agents canalso function by improving the ratio of specific signal produced byreaction of the composition with a phosphatase enzyme to backgroundchemiluminescence. Preferred compounds which are effective in reducingthe amount of background chemiluminescence include sulfite salts such aslithium sulfite, sodium sulfite and potassium sulfite.

A preferred composition for detection of AP or conjugates in solutioncomprises an amine buffer, pH 8.5-9, 0.1-1000 μm lucigenin, 0.1-1.0 mMcompound 5, 0.1-5 mg/mL SDS, 1-100 μg/mL Na₂SO₃, 0.01-0.1% (w/v) TWEEN20 and 0.1-1.0 mM Mg salt. A preferred composition for detection of APor conjugates on a membrane comprises an amine buffer, pH 8.5-9,0.1-1000 μM lucigenin, 0.1-1.0 mM compound 5, 0.1-5 mg/mL SDS, 1-100μg/mL Na₂SO₃, 0.01-0.1% (w/v) TWEEN 20 and 0.1-1.0 mM Mg salt.

Compositions which are effective in the present method can function byincreasing the fraction of excited state product molecules which emitlight, by increasing the fraction of product molecules which are formedin the excited state, by increasing the rate of reaction or turnover ofthe enzyme, by increasing the rate of a subsequent chemical reactionstep, by improving the stability of the enzyme, by promoting theassociation of the enzyme with the compound of formula I, by inhibitingor preventing competitive non-luminescent side reactions or by other asyet unidentified mechanisms.

It is contemplated that fluorescent energy acceptors can be employed toshift the maximum emission to longer wavelengths (red-shifting). Varioustechniques for red-shifting emission are known in the art ofchemiluminescent reactions and assays. The fluorescer can be covalentlylinked to a compound of formula I-V whereby the excited state of thecorresponding compound VI can undergo an intramolecular energy transferresulting in emission at longer wavelengths. Fluorescers can be added tothe reaction solution as separate species. Fluorescers can be linked toan anionic or non-ionic surfactant which can form a micelle in order tobring the fluorescer in close contact to the light emitter. Alternately,the fluorescer can be provided in a non-fluorescent form which isconvertible to the fluorescent form by removal of a phosphate groupduring the enzyme reaction period. Examples of the latter type ofcompound include fluorescein diphosphate, coumarin phosphates such as4-methylumbelliferone phosphate and benzothiazole phosphates such asATTOPHOS (JBL Scientific, San Luis Obispo, Calif.).

An important use of the present chemiluminescent methods is fordetecting the presence or amount of an analyte in an assay procedure bya chemiluminescent reaction. The method comprises the steps ofcontacting a sample suspected of containing the analyte with achemiluminescent compound of the present invention and a phosphataseenzyme, detecting the light produced in a qualitative method and, ifquantitation is desired, relating the amount of light produced to theamount of the analyte. The relationship between light intensity andamount of analyte can be easily discerned by constructing a calibrationcurve with known amounts of the analyte. The chemiluminescent compoundis typically used in a concentration of about 10⁻⁵ M to about 10⁻² M,preferably between about 10⁻⁴ M and about 10⁻³ M. The phosphatase enzymeis preferably below about 10⁻⁹ M when detected in a solution. Typicalsamples which are analyzed by the chemiluminescent reaction method arebody fluids such as blood, plasma, serum, urine and semen.

Analyte as used herein means a substance whose presence can be detectedor quantified in a sample. Analytes which can be assayed by the presentmethods include phosphatase enzymes, in which case it would beunnecessary to add additional phosphatase enzyme. The analyte can be aninhibitor of a phosphatase enzyme. The analyte can be any of variousclasses of organic and biological molecules which can be detected inligand-binder assays as are generally known in the art and includeimmunoassays, nucleic acid probe assays, cell receptor assays and thelike. In these assays, the analyte is labeled with a phosphatase enzymeor can be specifically detected through phosphatase-labeled specificbinding partners. The phosphatase can be incorporated directly as thelabel on the analyte binding compound. Alternately, the analyte bindingcompound can be bound to at least one phosphatase-labeled specificbinding substance for the analyte binding compound. Alternately, theanalyte binding compound can be labeled with at least one secondspecific binding substance which is then bound to a phosphatase-labeledbinding partner for the second specific binding substance. Thephosphatase enzyme can also be provided as a label on a ligand analogsuch as an enzyme-hapten conjugate in a competitive assay.

The phosphatase enzyme which can undergo the chemiluminescent reactioninclude alkaline phosphatase from a bacterial source such as E. coli, ora mammalian alkaline phosphatase or acid phosphatase from plant ormammalian sources. Conjugates of a phosphatase enzyme and a biologicalmolecule can also be used in the method for producing chemiluminescence,the only proviso being that the conjugate display phosphatase activity,i.e. the ability to hydrolyze phosphate monoesters. Biological moleculeswhich can be conjugated to one or more molecules of a phosphatase enzymeinclude DNA, RNA, oligonucleotides, antibodies, antibody fragments,antibody-DNA chimeras, antigens, haptens, proteins, lectins, avidin,streptavidin and biotin. Complexes including or incorporatingphosphatase enzymes such as liposomes, micelles, vesicles and polymerswhich are functionalized for attachment to biological molecules can alsobe used in the methods of the present invention.

The reaction of a composition of the present invention with aphosphatase enzyme to produce chemiluminescence constitutes a rapid andhighly sensitive method for detecting the presence or amount of thephosphatase enzyme. Use of the present method can therefore be made forthe purpose of determining the presence or quantity of a phosphataseenzyme in a sample by measuring the amount or intensity of lightproduced by reaction of the sample with a compound of formula I. Such adetermination can be used e.g. in measuring the level of alkalinephosphatase in blood serum as an indication of the status of a patient'sliver function or as an index of certain disease conditions. Prostaticacid phosphatase is also useful as a clinical diagnostic index ofprostate cancer.

Compositions of the present invention are useful for measurement of acidphosphatase (AcP) produced chemiluminescence which rapidly reachesmaximum intensity within 2-5 sec and then decays within a short periodof time. Even though the pH of the compositions is far higher than theoptimal pH for AcP activity, it is possible to quantitate this enzymewith good sensitivity. Moreover,

AcP could be measured in the presence of AP by means of this detectionreagent. Since the chemiluminescent signal induced by AcP and AP displaydifferent kinetics, it is possible to simultaneously determine both AcPand AP activities in the same sample in one experiment.

A second area of application for the chemiluminescent measurement ofphosphatase activity is in the detection and measurement of enzymeinhibitors. Inhibitors can act reversibly by acting as a substrate incompetition with a second substrate such as the compounds of the presentinvention. Another mode of inhibition known as suicide inhibition actsirreversibly by deactivating the enzyme. Inhibitors of alkalinephosphatase include inorganic phosphate, levamisole and its racemic formtetramisole and other imidazo[1,2-b]thiazoles, L-phenylalanine andL-homoarginine and are identified in R. B. McComb, G. N. Bowers, S.Posen in Alkaline Phosphatase, Plenum Press, New York 1979, pp. 268-275,332-334, 394-397, 410-413. Inhibitors of acid phosphatase includefluoride, molybdate, orthophosphate ions, tartrate,4-(fluoromethyl)phenyl phosphate and 4-(fluoromethyl)phenyl phosphonate(J. K. Myers, T. S. Widlanski, Science, 262, 1451-3 (1993)). It isrecognized that some substances are only inhibitory at someconcentrations and can be only partially inhibitory.

Measurement of the quantity or characteristics of an inhibitor, such asthe inhibition constant K_(i), or half-life for inhibition, t_(½), aremade by measuring the enzyme activity of a sample containing the enzymein question in the presence of a substrate producing a detectableproduct and a quantity of the inhibitor. In a method of detecting aphosphatase inhibitor according to the present invention, a compound offormula I produces light as the detectable product. Reaction of thephosphatase enzyme and chemiluminescent compound is made in the presenceand absence of the inhibitor substance and the results are compared todetermine the presence or amount of the inhibitor. The effect of theinhibitor can have one or more of any of three effects, a decrease inlight intensity, a slower rate of rise of light intensity or a delayperiod before light emission begins.

A third area of application for the chemiluminescent measurement ofphosphatase activity is in gene expression assays. Alkaline phosphataseand in particular an isozyme produced in the placenta which is excretedare useful as reporter genes (J. Alam, J. Cook, Anal. Biochem. 188,245-54 (1990)). In this type of assay, a gene responsible for expressionof a reporter enzyme is cloned into the genetic material of an organismvia a plasmid in the vicinity of a promoter or enhancer sequence. Theeffect of the promoter or enhancer sequence on transcriptional activityis gauged by measuring the level of production of reporter enzyme.

Techniques for performing enzyme assays are well known. With theguidance provided by the examples as taught herein, variations ofprocedures for preparing samples, determining appropriate quantities andratios of reagents, reaction times, constructing calibration curves andthe like will be within the ability of one of ordinary skill in the artto devise as a matter of routine experimentation.

Since the reaction is catalyzed by the phosphatase enzyme, exceedinglysmall quantities of the enzyme are sufficient to produce a detectableamount of light. Sensitivities of 4 zeptomol (4×10⁻²¹ mol) have beenachieved. The ability to detect such small amounts of phosphataseenzymes make the present chemiluminescent technology suitable foranalyses of many types of analytes using enzyme-linked assays. Suchanalyses and assays require the ability to detect small quantities ofphosphatase enzymes due to low abundance of the analyte in the sample tobe analyzed or to limited sample quantity. In this type of assay,alkaline phosphatase is conjugated to one member of a specific bindingpair. An example is a chemiluminescent enzyme-linked immunoassays, suchas the so-called enzyme-linked immunosorbent assay or ELISA. Such assaysare commonly used in manual format as well as on automated multi-testimmunoassay systems. In a typical immunoassay, the analyte hapten,antigen or antibody is assayed by detecting the presence or amount of anenzyme-labeled specific binding partner for the analyte or anenzyme-labeled analog of the analyte. Various assay formats and theprotocols for performing the immunochemical steps are well known in theart and do not constitute a part of the invention per se. These assaysfall broadly into two categories. Competitive assays feature animmunological binding of a specific antibody with the analyte and ananalyte analog, e.g. a detectably labeled analyte molecule. Sandwichassays result by the sequential or simultaneous binding of twoantibodies, one of which is detectably labeled, with the analyte. Thedetectable enzyme-labeled binding pair so formed can be assayed with thecompounds and methods of the present invention. Measurement can beperformed with enzyme-labeled species attached to a solid surface orsupport including beads, tubes, microwells, magnetic particles, teststrips, membranes and filters such as are in common use in the art. Thedetectable enzyme-labeled species can also be present free in solutionor enclosed within an organized assembly such as a liposome in whichcase a lytic agent is employed to lyse the liposome and free thedetectable enzyme.

Another exemplary use is the detection of proteins by the technique ofWestern blotting. A sample containing a protein of interest as theanalyte is subject to electrophoretic separation. The separated proteinsare transferred to a blotting membrane by capillary action or with theaid of an electric field. Such transferred protein is typically detectedwith a specific primary antibody and an enzyme-labeled secondaryantibody which recognizes and binds to the primary antibody.Visualization of marker enzyme activity reflects the presence of theanalyte protein. To adapt the methods of the present invention forWestern blotting, an AP conjugated secondary antibody can be employedand AP activity measured with chemiluminescence using a compound of thepresent invention as the chemiluminescent reagent. Variations on thistechnique such as using biotinylated antibodies and avidin-AP areconsidered within the scope of assays able to be performed using theinventive methods.

In addition to the aforementioned antigen-antibody, hapten-antibody orantibody—antibody pairs, specific binding pairs also can includecomplementary oligonucleotides or polynucleotides, avidin-biotin,streptavidin-biotin, hormone-receptor, lectin-carbohydrate, IgG-proteinA, nucleic acid-nucleic acid binding protein and nucleicacid-anti-nucleic acid antibody.

A particularly useful application of the present detection methods isthe detection of nucleic acids by the use of enzyme-labeled nucleic acidprobes. Methods for analysis and chemiluminescent detection of nucleicacids using enzyme-labels, for example, hybridization assays, DNAdetection in Southern blotting, RNA by Northern blotting, DNAsequencing, DNA fingerprinting, colony hybridizations and plaque liftsare all well established techniques. The enzyme label (e.g. AP) can bepresent as a direct conjugate with a probe oligonucleotide or captureoligonucleotide or it can be incorporated through indirect linking meansusing art-know methods. Examples of indirect linking means include usinghapten-labeled oligonucleotides and anti-hapten-AP conjugates orbiotinylated oligonucleotides and avidin-AP conjugates. Such nucleicacid assays can be performed on a blotting membrane or in solution usingoligonucleotides attached to solid surfaces including beads, tubes,microwells, magnetic particles, test strips such as are known in theart.

Process for the Preparation of Compounds I-IV. A process andintermediates useful for the preparation of chemiluminescent phosphatecompounds I-IV of the present invention was disclosed and embodied inthe co-pending 585,090 application. For the purposes of elaboratingadditional exemplary methods and conditions, the following additionalexplanatory information is presented.

Briefly, the process involves reacting a heterocyclic ester or thioestercompound VIII with a base to form an enolate of VIII; phosphorylatingthe enolate of VIII by reacting the enolate with a phosphorylating agentto form a protected enol phosphate IX and deprotecting the enolphosphate to form the enol phosphate salt compound I by reacting IX withat least one deprotecting agent in the presence of a cationic species Mif the cationic species is not a part of the deprotecting agent.

In one embodiment, the protected enol phosphate IX is formed by firstreacting the enolate of compound VIII with a phosphorus oxyhalidecompound POW₃, where W is a halogen atom selected from F, Cl, Br and Ito form an enol dihalophosphate X. The intermediate enol dihalophosphateX is converted to protected enol phosphate IX by reaction with at leasttwo equivalents of a hydroxylic compound Y—OH. The phosphate triester IXis then converted to phosphate salt I by reaction with at least onedeprotecting agent in the presence of a cationic species M if thecationic species is not a part of the deprotecting agent.

Preferably the halogen W is Cl. Compounds which can serve as thehydroxylic compound Y—OH include, without limitation, lower alcoholssuch as methanol and ethanol, substituted lower alcohols such as3-hydroxypropionitrile (HOCH₂CH₂CN) and 2-trimethylsilylethanol, phenol,substituted phenols, benzyl alcohol and others as are generally known.

In another embodiment, the protected enol phosphate IX can be prepareddirectly from VIII by reacting the enolate of VIII a phosphorylatingagent containing the protecting groups Y and having the formulaW—PO(OY)₂.

The groups O—Y in this phosphorylating agent can include, by way ofexample, alkoxy such as OCH₃, OCH₂CH₃, and the like, substituted alkoxysuch as cyanoethoxy (OCH₂CH₂CN) or trimethylsilylethoxy(OCH₂CH²Si(CH₃)₃), phenoxy, substituted phenoxy, benzyloxy and others asare generally known to the skilled organic chemist. The two groups O—Ycan also be combined together as a single group as occurs in the reagent

The enolate is formed by reacting the ester or thioester compound VIIIwith a strong base in a non-reactive organic solvent at a temperature inthe range of −90 to 25° C. In a preferred mode, the reaction isperformed at the temperature of a dry ice/acetone bath, nominally −78°C. for a time and then allowed to warm to 0 to 25° C. for a second time.Suitable solvents are those non-protic solvents which are compatiblewith the strong base required to form the enolate and include ethers andhydrocarbon solvents. The preferred solvent is tetrahydrofuran. Thestrong base and carbonyl compound VIII can be added to the reactionvessel in either order.

The phosphorylation step is performed in the same solution at atemperature in the range of about −78° C. to about 25° C. Thephosphorylating agent, either POW₃ or WPO(OY)₂ is added in a controlledfashion so as not to cause the reaction solution to become hot. Thephosphorylation agent is preferably accompanied by an amine base,preferably pyridine.

The deprotection step is accomplished by reacting the protected enolphosphate IX with a deprotecting agent in a quantity sufficient to causeremoval of the protecting groups and in the presence of a cationicspecies M if the cationic species is not a part of the deprotectingagent. Two equivalents of the deprotecting agent are typically required,however for convenience, the deprotecting agent can be used in molarexcess. Removal of the protecting groups can in some cases be performedone at a time. For example, in a compound of formula XI wherein the twoY groups together constitute the single group —CH₂CH₂—, and thereby forma five-membered ring, the first O—CH₂ bond can be cleaved by treatmentwith a cyanide salt. The resulting compound XII is further reacted witha base to cleave the second O—CH₂ bond and generate the salt I.

The choice of the deprotecting agent will be determined, in part, by thenature of the groups Y to be removed. The deprotecting agent must alsonot cause undesired side reactions such as hydrolysis of the vinyl etheror vinyl sulfide group or undesired changes to the heterocyclic group.Preferred deprotecting agents include organic and inorganic bases suchas sodium hydroxide, potassium hydroxide, potassium carbonate, sodiummethoxide, sodium ethoxide, potassium t-butoxide, ammonium hydroxide andthe like. Other preferred deprotecting agents include nucleophilicagents such as cyanide ion, fluoride ion.

To the best of applicant's knowledge, compounds IX, X, XI and XII inwhich Het is a nitrogen or sulfur-containing heterocyclic group have notbeen prepared. An enol phosphate ester compound in which anoxygen-containing lactone ring is appended to the double bond isdisclosed in U.S. Pat. No. 3,130,203. This compound however was preparedby a different process, not involving phosphorylation of an ester orthioester enolate.

EXAMPLES

The preparation and chemiluminescent reaction of the following compoundsof formula I are described below for purposes of illustrating theinvention in more detail.

Compound R₇-R₁₄ Z R6 1 all H O phenyl 2 all H O 3,5-difluorophenyl 3 R₉= OCH₃ O phenyl 4 R₉ = Cl O 2,6-dimethylphenyl 5 all H S phenyl 6

O phenyl 7 all H S 4-fluorophenyl 8 all H S 4-methoxyphenyl 9 all H S2,6-dimethylphenyl 10 R₈, R₁₃ = F S phenyl 11 all H S trifluoroethyl 12all H S 4-chlorophenyl 13 all H S 2-naphthyl R₇-R₁₄ are H unlessotherwise indicated.

Each of compounds 1-13 was prepared by the following synthetic scheme.It will be recognized that modifications to the reaction conditions canbe made within the confines of the synthetic process described above inorder to prepare these and other compounds of formula I.

Example 1 Synthesis of Acridan Derivative 1

a. Phenyl acridine-9-carboxylate. Acridine-9-carboxylic acid (1 g, 4.1mmol) was suspended in thionyl chloride (5 mL) and the reaction mixturewas refluxed for 3 h. The solvent was removed under reduced pressureleaving a yellow solid which was dissolved in CH₂Cl₂ and pyridine (350μL) under argon. This solution was cooled in an ice bath and a solutionof phenol (0.78 g, 8.2 mmol) in CH₂Cl₂ was added dropwise. The reactionmixture was stirred overnight at room temperature. After evaporation ofsolvent, the residue was redissolved in ethyl acetate and washed withwater. The organic layer was dried over MgSO₄ and concentrated to obtaina crude material which was chromatographed on silica gel (30% ethylacetate/hexane) to yield the pure product as a yellow solid. ¹H NMR(CDCl₃) δ7.35-7.57 (m, 5H), 7.63-8.37 (m, 8H).

b. Phenyl 10-methylacridinium-9-carboxylate trifluoromethanesulfonate.Phenyl acridine-9-carboxylate (530 mg, 1.7 mmol) was dissolved in CH₂Cl₂(5 mL) under argon and methyl triflate (1 mL, 8.8 mmol) was added. Thesolution was stirred overnight at room temperature to yield a thickyellow precipitate. This precipitate was filtered, washed with ether anddried to obtain the product as yellow crystals. ¹H NMR (acetone-d₆)δ5.22 (s, 3H), 7.47-7.71 (m, 5H), 8.23-9.07 (m, 8H).

c. Phenyl 10-methylacridan-9-carboxylate. Phenyl10-methylacridinium-9-carboxylate trifluoromethanesulfonate (10 mg,0.0216 mmol) was suspended in absolute ethanol (10 mL) and the mixturewas refluxed for 15 min to obtain a clear solution. Ammonium chloride(88 mg, 1.6 mmol) was added by portions to the solution followed by zinc(108 mg, 1.6 mmol). Addition of zinc caused the yellow color of thesolution to disappear immediately. The colorless solution was refluxedfor 2 h. TLC of the reaction mixture showed complete conversion to a nonpolar material. The solution was filtered and precipitate was washedwith ethanol (3×20 mL). The filtrate was concentrated to obtain anoff-white solid which was redissolved in CH₂Cl₂ and washed with water(2×15 mL). The organic layer was dried over Na²SO⁴ and concentrated toyield the crude product which was purified by preparative TLC using (30%ethyl acetate:hexane). Pure product was obtained as an off-white solid.¹H NMR (CDCl₃) δ3.38 (s, 3H), 5.16 (s, 1H), 6.89-7.37 (m, 13H); ¹³C NMR(CDCl₃) δ33.29, 49.72, 112.93, 120.19, 121.36, 125.73, 128.67, 129.16,129.26, 142.37, 151.04, 170.22.

d. 9-(Phenoxyphosphoryloxymethylidene)-10-methylacridan, bis(cyanoethyl)ester. A three-neck flask was purged with argon and charged with 5 mL ofanhydrous THF and diisopropylamine (0.04 mL, 0.29 mmol). The flask wascooled in a dry ice-acetone bath. To this solution was added n-butyllithium (0.116 mL, 0.29 mmol). After 20 min, a solution of the acridanester from step (c)(70 mg, 0.22 mmol) in 5 mL of THF was added to thissolution and stirring was continued for 30 min at −78° C. Finally asolution of POCl₃ (0.027 mL, 0.29 mmol) and pyridine (0.023 mL, 0.29mmol) in 3 mL of THF was added and the dry ice bath was removed. After45 min, pyridine (0.039 mL, 0.58 mmol) and 3-hydroxypropionitrile (0.094mL, 1.16 mmol) was added and stirring maintained over night. Then it wasfiltered and solvent was removed from the filtrate. The residue wassubjected to prep. TLC (80% ethyl acetate/hexane) to give the pureproduct; ¹H NMR (CDCl₃) δ2.35-2.54 (m, 4H), 3.47 (s, 3H), 3.79-3.90 (m,2H), 3.98-4.08 (m, 2H), 6.825-7.45 (m, 12H), 7.80-7.83 (dd, 1H); ¹³C NMR(CDCl₃) δ19.12, 19.24, 33.63, 62.19, 62.49, 88.72, 92.82, 112.40,112.52, 115.83, 116.07, 119.68, 120.44, 120.71, 123.81, 126.69, 128.03,128.27, 128.58, 130.09, 142.39, 143.06, 165.73, 202.09.

e. 9-(Phenoxyphosphoryloxymethylidene)-10-methylacridan, disodium salt(1). A solution of the bis(cyanoethyl) phosphate compound (2.897 g, 5.77mmol) in 50 mL of acetone was purged with Ar for 30 min. An Ar-purgedsolution of 479 mg (12 mmol) of NaOH in 7.5 mL of water was addeddropwise and the solution stirred over night. The precipitate which hadformed was filtered, washed with 50 mL of Ar-purged acetone andair-dried. The yield was 3.473 g of 1 as a white solid which containedsome water. ¹H NMR (D₂O) δ3.326 (s, 3H), 6.825-7.45 (m, 11H), 7.80-7.83(d, 1H); ¹³C NMR (D₂O) δ32.95, 102.86, 102.92, 112.30, 115.85, 120.68,121.01, 122.35, 122.41, 122.62, 127.48, 127.66, 128.23, 129.66, 143.17,143.32, 144.66, 156.01; ³¹P NMR (D₂O) δ0.581 (rel. to ext. H₃PO₄).

Example 2 Synthesis of Acridan Derivative 2

a. 3′,5′-Difluoroohenyl acridine-9-carboxylate. Acridine-9-carboxylicacid (0.25 g) was suspended in 10 mL thionyl chloride and the reactionmixture was refluxed for 3 h. The solvent was removed under reducedpressure to obtain a yellow solid which was dissolved in CH₂Cl₂ andpyridine (0.22 g) under argon. A solution of 3,5-difluorophenol (0.16 g)in CH₂Cl₂ was added dropwise. The solution was stirred overnight at roomtemperature then diluted with more CH₂Cl₂ (100 mL) and washed with water(3×50 mL). The organic layer was dried over Na₂SO₄ and concentrated toobtain the product which was further purified by chromatography onsilica gel (30% ethyl acetate/hexane) to yield the pure product as acreamy solid. ¹H NMR (CDCl3) δ6.84-7.09 (m, 3H), 7.67-8.37 (m, 8H).

b. 3′,5′-Difluorophenyl 10-methylacridinium-9-carboxylatetrifluoromethanesulfonate. The acridine ester from step (a) (0.20 g) wasdissolved in CH₂Cl₂ (5 mL) under argon and methyl triflate (0.472 mL 7eq.) was added. The solution was stirred overnight at room temperatureto yield a thick yellow precipitate. This precipitate was filtered,washed with ether and dried to obtain the product as yellow crystals. ¹HNMR (acetone-d₆) δ5.25 (s, 3H), 7.22-7.59 (m, 3H), 8.23-9.09 (m, 8H).

c. 3′,5′-Difluorophenyl 10-methylacridan-9-carboxylate. The acridiniumester from step (b) (0.10 g) was dissolved in 10 mL of glacial aceticacid to obtain a yellow solution and zinc was added (1.30 g) causingimmediate decolorization of the solution. After 5 min stirring at roomtemperature, TLC of the reaction mixture showed a nonpolar material. Theacetic acid was decanted and the solid washed with CH₂Cl₂. The combinedorganic solutions were evaporated to obtain a crude solid which wasredissolved in CH₂Cl₂ and washed with 2 or 3-50 mL portions of water.The crude material obtained after evaporation of CH₂Cl₂ waschromatographed on silica gel (20-30% ethyl acetate/hexane) to yield thepure product as a white solid. ¹H NMR (CDCl₃) δ3.44 (s, 3H), 5.16 (s,1H), 6.49-6.65 (m, 3 H), 6.99-7.36 (m, 8H).

d. 9-(3,5-Dimethylphenoxy)phosyloxymethylidene)-10-methylacridan.bis(cyanoethyl) ester. A three-neck flask was purged with argon andcharged with 4 mL of anhydrous THF and diisopropylamine (0.0494 mL, 0.35mmol). The flask was cooled in a dry ice-acetone bath. To this solutionwas added n-butyllithium (0.141 mL, 0.35 mmol). After 20 min, a solutionof the acridan ester from step (c)(75 mg, 0.22 mmol) in 4 mL of THF wasadded dropwise to the LDA. The funnel was washed with an additional 4 mLof Ar-purged THF which was added to the reaction solution. Stirring wascontinued for 30 min at −78° C. Finally a solution of POCl₃ (0.034 mL,0.35 mmol) and pyridine (0.057 mL, 0.35 mmol) in 4 mL of THF was addedcausing the brown solution to decolorize. The dry ice bath was removedand stirring continued for 15 min. A solution of pyridine (0.095 mL,1.17 mmol) and 3-hydroxypropionitrile (0.080 mL, 1.17 mmol) in 4 mL ofTHF was added and stirring maintained over night. Then it was filteredand the solvent was removed from the filtrate. The residue was subjectedto prep. TLC (55% ethyl acetate/hexane) from which a small amount of thepure product was isolated; ¹H NMR (acetone-d₆) δ2.82 (m, 4H), 3.51 (s,3H), 4.10-4.31 (m, 4H), 6.75-7.93 (m, 11H).

e. 9-(3,5-Dimethylphenoxy)phohosphoryloxymethylidene)-10-methylacridan.disodium salt (2). A solution of the bis(cyanoethyl)phosphate from step(d) 5 mg, 5.77 mmol) in 5 mL of methanol was purged with argon for 30min with ice cooling. An Ar-purged solution of 6 mg of Na₂CO₃ in 0.5 mLof water was added dropwise and the solution stirred under argon over aweekend. The solvent was evaporated and the solid compound 2 dried undervacuum. ¹H NMR (D₂O) δ3.34 (s, 3H), 6.66-8.09 (m, 11H).

Example 3 Synthesis of Acridan Derivative 3

a. N-Methyl-3-methoxyisatin. 3-methoxydiphenylamine (250.2 g, 1.26 mol)dissolved in 900 mL of CH₂Cl₂ was added to a hot solution of 140 mL (1.6mol) of oxalyl chloride in 1 L of CH₂Cl₂under an argon atmosphere. Theaddition was completed over a 2 hour period. Heating was discontinuedduring the addition since the reaction produced enough heat to maintainreflux. Stirring was continued at reflux temperature for another 30 minafter adding the amine. The resulting brown solution was evaporated toremove excess oxalyl chloride. The brown solid was redissolved in 1.8 Lof CH₂Cl₂ which was purged with argon. Aluminum chloride (359 g, 2.69mol) was added in portions to the solution over a 45 min period whilethe mixture was stirred mechanically. The mixture became thick duringthe addition and began to reflux. Reflux was maintained for anadditional hour after all of the AlCl₃ had been added. The cooledmixture was evaporated in vacuo and quenched with 4 kg of ice, ca. 500mL of water and 240 mL of conc. HCl. The dark solid was carefullycrushed to small particles while stirring at ice temperature for 2 h.The solid was then filtered off with suction and washed with a total of8 L of water. Air drying produced an orange solid which was a mixture ofisomeric isatins containing >90% of one isomer.

b. 3-Methoxyacridine-9-carboxylic acid. The isatin mixture from step (a)was refluxed in a 10% KOH solution in water for ca. 40 h. The solutionwas cooled to <60° C. and filtered through glass wool into a mixture of480 mL of conc. HCl and 10 L of ice water which was stirred vigorously.The solid was suction filtered after 1 h and then washed with 8 L ofwater. The solid was air-dried over night and then dried under vacuum.¹H NMR (CD₃OD/NaOH) δ4.062 (s, 3H), 7.25-8.18 (m, 7H).

c. Phenyl 3-methoxyacridine-9-carboxylate.3-Methoxyacridine-9-carboxylic acid (0.50 g) was suspended in 10 mLthionyl chloride (3-10 mL) and reaction mixture was refluxed for 3 h.The solvent was removed under reduced pressure to obtain a yellow solidwhich was dissolved in CH₂Cl₂ and pyridine (0.44 g) under argon. Asolution of 2,6-difluorophenol (0.32 g) in CH₂Cl₂ was added dropwise.The solution was stirred overnight at room temperature then diluted withmore CH₂Cl₂ (100 mL) and washed with water (3×50 mL). The organic layerwas dried over Na₂SO₄ and concentrated to obtain the product which wasfurther purified by chromatography on silica gel (30% ethylacetate/hexane) to yield the pure product as a creamy solid. ¹H NMR(acetone-d₆) δ4.08 (s, 3H), 7.39-8.29 (m, 12H).

d. Phenyl 3-methoxyacridan-9-carboxylate. Ammonium chloride (3.45 g, 64mmol) and 4.2 g of zinc (64 mmol) were added to an Ar-purged suspensionof 0.85 g (2.5 mmol) of the ester from step (c) in 50 mL of ethanol. Themixture was stirred for 2 h, filtered and the solids washed with CH₂Cl₂.The combined solutions were evaporated to dryness producing a whitesolid which was dissolved in ethyl acetate and washed with 3×25 mL ofwater. The product was used without further purification. ¹H NMR (CDCl3)δ3.76 (s, 3H), 5.29 (s, 1H), 6.47-7.36 (m, 12H), 8.21 (br s, 1H).

e. Phenyl 3-methoxy-10-methylacridan-9-carboxylate. The acridan compoundfrom the previous step (0.77 g, 2.3 mmol) was dissolved in CH₂Cl₂ andmethyl triflate (3.8 g, 23 mmol) was added. TLC indicated completemethylation after stirring over night. The volatiles were evaporated andthe residue purified by chromatography using 18% ethyl acetate/hexane toelute the column. The product contained 0.75 g of a sticky solid. ¹H NMR(CDCl3) δ3.41 (s, 3H), 3.84 (s, 3H), 5.13 (s, 1H), 6.52-7.38 (m, 12H).

f.(E,Z)-9-(Phenoxy)phosphoryloxymethylidene)-3-methoxy-10-methylacridan,bis(cyanoethyl) ester. A solution of LDA was prepared essentially asdescribed in Example 2d. After stirring 25 min at −78 C., a solution ofthe acridan ester from step 3e (95 mg, 0.26 mmol) in 4 mL of THF wasadded dropwise. Stirring was continued for 30 min at −78° C. Finally asolution of POCl₃ (0.04 mL) and pyridine (0.05 mL) in 4 mL of THF wasadded causing the yellow solution to decolorize. The dry ice bath wasremoved and stirring continued for 105 min. The solution was cooled inan ice bath and treated with pyridine (0.106 mL) and3-hydroxypropionitrile (0.090 mL) in 4 mL of THF. After stirring for 20h at room temperature, the reaction mixture was filtered and the yellowprecipitate washed with THF. The reaction solvent was evaporated invacuo and the residue combined with the precipitate. This material wassubjected to prep. TLC (60% ethyl acetate/hexane) from which a smallamount of the product was isolated as a mixture of double bond isomers;¹H NMR (acetone-d₆) δ2.75-2.82 (m, 4H), 3.52 (s, 3H), 3.82 (s), 3.91(s), 4.00-4.26 (m, 4H), 6.47-7.96 (m, 12H).

g.(E,Z)-9-(Phenoxy)phosphoryloxymethylidene)-3-methoxy-10-methylacridan,disodium salt (3). The bis(cyano-ethyl)phosphate from step 3(f) wasdissolved in 10 mL of MeOH purged with Ar and cooled in an ice bath. AnAr-purged solution of 11 mg of Na₂CO₃ in 1 mL of water was addeddropwise and the solution stirred for 19 h. Another 3 mL of methanol wasadded and stirring continued for another 24 h to allow the deprotectionto go to completion. The solvent was evaporated, the solid compound 3washed with CH₂Cl₂ and dried under vacuum. ¹H NMR (D₂O) δ3.24 (s, 3H),3.66 (s), 3.83 (s), 6.35-8.07 (m, 12H).

Example 4 Synthesis of Acridan Derivative 4

a. 3-Chloroisatin. 3-Chlorodiphenylamine (20 g, 0.98 mol) dissolved in250 mL of CH₂Cl₂ was added to a solution of 14.0 g (0.11 mol) of oxalylchloride in 150 mL of CH₂Cl₂ under an argon atmosphere. The solution wasrefluxed for 30 min. The resulting solution was evaporated to removeexcess oxalyl chloride. The solid was redissolved in CH₂Cl₂ which waspurged with argon. Aluminum chloride (54.48 g) was added in portions tothe solution over a 45 min period while the mixture was stirredmechanically. The mixture became thick during the addition and began toreflux. Reflux was maintained for an additional hour after all of theAlCl had been added. The cooled mixture was evaporated in vacuo andquenched with 900 mL of 1M HCl in an ice bath. The solid was thenfiltered off with suction and washed with water. ¹H NMR (CDCl₃) δ6.8-7.8(m, 8H)

b. 3-Chloroacridinecarboxylic acid. The isatin product from step (a) wasrefluxed in 300 mL of 10% KOH solution in water for ca. 48 h. Thesolution was cooled and acidified to pH 2-3 with HCl. The yellow solidwas suction filtered after 1 h and then washed with water. The solid wasair-dried over night, washed with CH₂Cl₂ and then air-dried yielding23.76 g of the acridine acid. ¹H NMR (DMSO-d₆) δ7.72-8.30 (m, 7H).

c. 2′,6′-Dimethylphenyl 3-chloroacridinecarboxylate. The acid (3.0 g)was esterified with 2,6-dimethylphenol (2.24 g, 1.5 eq.) and pyridine(1.98 mL, 2 eq.) in ca. 100 mL of CH₂Cl₂ at room temperature undernitrogen. The solvent was evaporated and the residue purified by columnchromatography using 10-30% ethyl acetate/hexane which allowed theseparation of the 1-chloro-(minor) and 3-chloro-isomers; ¹H NMR (CDCl₃)δ2.430 (s, 6H), 7.20-7.28 (m, 3H), 7.60-7.75 (m, 3H), 8.28-8.50 (m, 4H).

d. 2′,6′-Dimethylphenyl 3-chloro-10-methylacridinium-carboxylatetrifluoromethanesulfonate. The acridine compound from the previous step(2.47 g, 6.7 mmol) was dissolved in CH₂Cl₂ and methyl triflate (3.8 mL,5 eq.) was added. TLC indicated complete methylation after stirring overnight. The volatiles were evaporated and the residue purified bychromatography using 5% ethyl acetate/hexane to elute the column. Theproduct was recrystallized from CH₂Cl₂/hexane yielding 1.7 g of whitecrystals.

e. 2′,6′-Dimethylphenyl 3-chloro-10-methylacridan-carboxylate. Ammoniumchloride (2.91 g, 64 mmol) and 3.56 g of zinc (64 mmol) were added to anAr-purged suspension of 2.00 g (5.4 mmol) of the ester from step (c) in50 mL of ethanol. The mixture was stirred for 2 h, filtered and thesolids washed with CH₂Cl₂. The combined solutions were evaporated todryness producing a white solid. The product was used without furtherpurification. ¹H NMR (CDCl₃) δ1.746 (s, 6H), 3.400 (s, 3H), 5.152 (s,1H), 6.88-7.04 (m, 7H), 7.26-7.39 (m, 3H).

f. (E,Z)-9-(2,6-Dimethylphenoxy)phosphoryloxymethylidene)-3-chloro-10-methylacridan,bis(cyanoethyl) ester. The acridan ester (0.100 g, 0.29 mmol) from step(e) was added to a solution of LDA (0.44 mmol) in 10 mL of THF. Afterstirring 30 min at −78 C., a solution of POC₃ (42 μL) and pyridine (47μL) in 4 mL of THF was added. The dry ice bath was removed and stirringcontinued for 30 min. TLC (30% ethyl acetate/hexane) showed that thestarting material was completely reacted. The solution was cooled in anice bath and treated with pyridine (117 μL) and 3-hydroxypropionitrile(94 μL) in 4 mL of THF. After stirring over night at room temperature,the precipitated was filtered away and the reaction solvent evaporated.The residue was subjected to prep. TLC (60% ethyl acetate/hexane) fromwhich the isomeric products was isolated; ¹H NMR (CD₃OD) δ(1.91 (s),1.95 (s), combined 3H), (2.03 (s), 2.04 (s), combined 3H), 2.69-2.76 (m,4H), (3.52 (s), 3.59 (s), combined 3H), 4.16-4.34 (m, 4H), 6.97-7.65 (m,10H).

g. (E,Z)-9-(2,6-Dimethylphenoxy)phosphoryloxymethylidene)-3-chloro-10-methylacridan,disodium salt (4). The bis(cyanoethyl)phosphate from the step above isdissolved in 10 mL of methanol purged with argon and then cooled in anice bath. An Ar-purged solution of 11 mg of Na₂ CO₃ in 1 mL of water isadded dropwise and the solution stirred under argon until thedeprotection has gone to completion. The solvent is evaporated, thesolid washed with CH₂Cl₂ and dried under vacuum to produce 4.

Example 5 Synthesis of Acridan Derivative 5

a. 9-(Phenythiophosphoryloxymethylidene)-10-methylacridan,bis(cyanoethyl) ester. Phenyl 10-methylacridan-9-thiocarboxylate (70 mg,0.2 mmol) was added to a solution of LDA (0.24 mmol) in THF. Afterstirring 30 min at −78 C., a solution of POCl₃ (25 μL) and pyridine (21μL) in 4 mL of THF was added. The dry ice bath was removed and stirringcontinued for 30 min. TLC (30% ethyl acetate/hexane) showed that thestarting material was completely reacted. The solution was cooled in anice bath and treated with pyridine (210 μL) and 3-hydroxypropionitrile(44 μL) in 4 mL of THF. After stirring over night at room temperature,the precipitated pyridine-HCl was filtered away and the reaction solventevaporated in vacuo. The residue was subjected to prep. TLC (ethylacetate) from which the product was isolated; ¹H NMR (CDCl₃) δ2.4-2.6(m, 4H), 3.521 (s, 3H), 3.8-4 (m, 2H), 4.0-4.1 (m, 2H), 6.9-7.2 (m, 4H),7.22-7.5 (m, 7H), 7.75-8 (dd, 2H).

b. 9-(Phenylthiophosphoryloxymethylidene)-10-methylacridan, disodiumsalt (5). A solution of the bis(cyanoethyl) phosphate compound (0.59 g,1.21 mmol) in 50 mL of acetone was purged with argon for 30 min. AnAr-purged solution of 104 mg (2.6 mmol) of NaOH in 10 mL of water wasadded dropwise and the solution stirred under argon over night. Theprecipitate which had formed was suction filtered, washed with 50 mL ofAr-purged acetone and air-dried. The yield was 0.50 g of 5 as a slightlyyellow solid which contained a slight amount of acetone. ¹H NMR (D₂O)δ3.36 (s, 3H), 6.9-7.4 (m, 11H), 7.75-7.8 (d, 1H), 8.2-8.22 (d, 1H); ³¹PNMR (D₂O) δ1.85 (rel. to ext. H₃PO₄).

Example 6 Synthesis of Benz[c]acridan Derivative 6

a. Benz[c]acridine-7-carboxylic acid. 1-Naphthylphenylamine (10 g, 46mmol) dissolved in 25 mL of CS₂ was refluxed with 4.8 mL (55 mmol) ofoxalyl chloride under argon. The resulting brown solution was evaporatedto remove excess oxalyl chloride. The brown solid was dissolved in 60 mLof CS₂ which was purged with argon. AlCl₃ (21.47 g, 160 mmol) was addedin portions to the solution while the mixture was stirred. The mixturebecame thick during the addition and began to reflux. Reflux wasmaintained for two more hours after all of the AlCl₃ had been added. Thecooled mixture was evaporated in vacuo and quenched with 1 M HCl andice. The dark solid was carefully crushed to small particles and thesolid filtered off with suction and washed with water.

The isatin product was refluxed in a 10% KOH solution in water overnight. The solution was cooled to <60° C. and neutralized with 6 M HCland ice. The solid was suction filtered, washed with water andair-dried. ¹H NMR (DMSO-d₆) δ7.80-8.13 (m, 8H), 8.36-8.39 (d, 1H),9.38-9.40 (m, 1H).

b. Phenyl benz[c]acridine-7-carboxylate. Benz[c]acridine-7-carboxylicacid (6.0 g) was suspended in 75 mL thionyl chloride (3-10 mL) andreaction mixture was refluxed for 4 h. The solvent was removed underreduced pressure and the product dissolved in 75 mL of CH₂Cl₂. Pyridine(8.9 mL) and phenol (2.27 g) were added and the solution was stirred for3 days at room temperature under Ar. Purification was effected bychromatography on silica gel (50% CH₂Cl₂/hexane) to yield 3.05 g of thepure product as a light brown solid. ¹H NMR (CDCl₃) δ7.40 (t, 1H),7.48-7.59 (m, 4H), 7.71-8.01 (m, 7H), 8.259 (d, 1H, J=7.8 Hz), 8.465 (d,1H, J=7.8 Hz), 9.54-9.57 (m, 1H).

c. Phenyl benz[c]acridan-7-carboxylate. Ammonium chloride (10 g) and 10g of zinc were added to an Ar-purged suspension of 1.0 g of the esterfrom step (b) in ethanol. The mixture was stirred for 2 h, filtered andthe solids washed with CH₂Cl₂. The combined solutions were evaporated todryness producing a white solid which was dissolved in ethyl acetate andwashed with 3×25 mL of water. The product was purified by chromatographyusing 10% ethyl acetate/hexane. ¹H NMR (CDCl₃) δ5.48 (s, 1H), 5.69-7.27(m, 9H), 7.41-7.55 (m, 5H), 7.83-7.88 (m, 2H).

d. Phenyl 12-methylbenz[c]acridan-7-carboxylate. The acridan compoundfrom the previous step (0.70 g) was dissolved in CH₂Cl₂ and methyltriflate (2.3 mL) was added. TLC indicated complete methylation afterstirring over night. The volatiles were evaporated and the residuepurified by chromatography using 5% ethyl acetate/hexane to elute thecolumn. ¹H NMR (CDCl₃) δ3.75 (s, 3H), 5.21 (s, 1H), 6.92-6.94 (d, 2H),7.09-7.62 (m, 11H), 7.86-7.89 (dd, 1H), 8.23-8.26 (d, 1H); ¹³C NMR(CDCl₃) δ45.07, 49.99, 120.01, 121.23, 122.66, 123.51, 124.69, 125.30,125.45, 125.84, 126.33, 126.97, 128.39, 128.64, 129.36, 134.89, 141.20,147.09, 151.00, 170.89.

e. (E,Z)-9-(Phenoxy)phosphoryloxymethylidene)-12-methylbenz[c]acridan,bis(cyanoethyl) ester. A solution of LDA was prepared as describedabove. After stirring 25 min at −78 C., a solution of the benzacridanester (0.30 g) in THF was added dropwise. Stirring was continued for 30min at −78° C. Finally a solution of POCl₃ (0.123 mL) and pyridine(0.107 mL) in THF was added causing the deep red solution to becomeorange. The dry ice bath was removed and stirring continued for 1 h. Thesolution was cooled in an ice bath and treated with pyridine (0.213 mL)and 3-hydroxypropionitrile (0.180 mL) in THF. After stirring over nightat room temperature, the reaction mixture was filtered and theprecipitate washed with THF. The reaction solvent was evaporated invacuo and the residue combined with the precipitate. This material wassubjected to prep. TLC (60% ethyl acetate/hexane) from which a smallamount of the product was isolated as a mixture of double bond isomers;¹H NMR (CDCl₃) δ2.44-2.52 (m, 4H), 3.81-4.10 (m, 7H), 6.89-8.24 (m,15H).

f. (E,Z)-9-(Phenoxy)phosphoryloxymethylidene)-12-methylbenz[c]acridan,disodium salt (6). The bis(cyanoethyl)phosphate from the step above wasdissolved in 10 mL of acetone purged with argon and then cooled in anice bath. An Ar-purged solution (0.1 mL of 2M NaOH in water) was addeddropwise and the solution stirred under Ar over night. The solid wasfiltered and the product compound 6 was washed with acetone and dried.¹H NMR (D₂O) δ3.52 (s, 3H), 6.85-6.90 (t, 1H), 7.03-7.06 (d, 2H),7.15-7.23 (m, 3H), 7.33-7.48 (m, 5H), 7.72-7.75 (d, 1H), 7.87-7.89 (d,1H), 8.10-8.17 (t, 2H).

Example 7 Synthesis of Acridan Derivative 7

a. 4′-Fluorophenyl acridine-9-thiocarboxylate. Acridine-9-carboxylicacid (10 g, 45 mmol) was suspended in thionyl chloride (ca. 100 mL) andthe reaction mixture was refluxed for 2 h. The solvent was removed underreduced pressure leaving a yellow solid which was dissolved in 100 mL ofCH₂Cl₂ under argon. 4-Fluorothiophenol (5.25 mL, 49 mmol) was addedfollowed by 30 mL of pyridine. The reaction mixture became reddish brownand warmed nearly to reflux. The mixture was stirred for 2 days at roomtemperature under argon. After evaporation of solvent, the residue waswashed with 800 mL of hexane, and then with a total of 1 L of water. Theremaining solid was dissolved in 300 mL CH₂Cl₂ and passed through a plugof Na₂SO₄/silica gel/Na₂SO₄. The thioester was obtained (11.55 g) as ayellow solid. ¹H NMR (CDCl₃) δ7.20 (t, 2H), 7.60-7.68 (m, 4H), 7.80-7.88(m, 2H), 8.129 (d, 2H), 8.278 (d, 2H).

b. 4′-Fluorophenyl 10-methylacridinium-9-thiocarboxylatetrifluoromethanesulfonate. 4′-Fluorophenyl acridine-9-thiocarboxylate(11.36 g, 34 mmol) was dissolved in CH₂Cl₂ (100 mL) under argon andmethyl triflate (20 mL) was added. The solution became brown andproduced a yellow precipitate. After 2 days, the precipitate wasfiltered, washed with 50 mL of CH₂Cl₂ and 500 mL of hexane and dried toobtain the product as yellow solid (15.3 g). ¹H NMR (DMSO-d₆) δ4.93 (s,3H), 7.53 (t, 2H), 7.97-8.37 (m, 2H), 8.14 (t, 2H), 8.54 (t, 2H), 8.61(d, 2H), 8.92 (d, 2H).

c. 4′-Fluorophenyl 10-methylacridan-9-thiocarboxylate. With roomlighting off, 4′-fluorophenyl 10-methyl-acridinium-9-thiocarboxylatetrifluoromethanesulfonate (15.05 g, 30 mmol) was suspended in 2-propanol(150 mL) and 2.1 mL of acetic acid. The solution was purged with argonfor 30 min. and then 10.0 g of zinc powder added. Addition of zinccaused the yellow color of the solution to disappear within minutes. Themixture was stirred over night. The mixture was filtered and the solidswashed with 2-propanol and then hexane. The remaining solid was washedwith CH₂Cl₂. Since a TLC analysis showed that the product had dissolvedin both solutions, the filtrates were concentrated and combined toobtain a brown solid which was redissolved in CH₂Cl₂ and passed througha plug of Na₂SO₄/silica gel/Na₂SO₄, eluting with CH₂Cl₂. A mixture ofthe expected acridan thioester and an acridan isopropyl ester resultingfrom transesterification was obtained. The two products were separatedby column chromatography (50% CH₂Cl₂:hexane). One fraction of pureacridan thioester product (2.5 g) was obtained as a white solid. Asecond fraction was obtained as a mixture with the isopropyl ester. ¹HNMR (CDCl₃) δ3.45 (s, 3H), 5.08 (s, 1H), 6.94-7.06 (m, 6H), 7.17-7.24(m, 2H), 7.31-7.39 (m, 4H).

d. 9-(4-Fluorophenylthiophosphoryloxymethylidene)-10-methylacridan,bis(cyanoethyl) ester. With room lighting off, 4-fluorophenyl10-methylacridan-9-thiocarboxylate (1.00 g, 2.87 mmol) in 10 mL ofanhydrous THF was added dropwise to a solution of LDA in THF at −78 C.After stirring 60 min at −78 C., the yellow solution was treated with asolution of POCl₃ (0.79 g) and pyridine (3.0 mL) in 10 mL of THF over a25 minute period. The dry ice bath was removed after an additional hourand stirring continued for 2 h. The solution was cooled in an ice bathand treated with 3-hydroxypropionitrile (0.71 mL) and the ice bathremoved after the addition was complete. After stirring over night atroom temperature, the precipitated pyridine-HCl was filtered off andwashed with 50 mL of THF. The combined filtrates were evaporated invacuo. The residue was separated by column chromatography using 50-100%ethyl acetate/hexanes from which the 0.658 g of the product wasisolated; ¹H NMR (CDCl₃) δ2.44-2.64 (m, 4H), 3.49 (s, 3H), 3.86-4.16 (m,4H), 6.92-7.15 (m, 6H), 7.26-7.46 (m, 4H), 7.786 (d, 1H), 7.906 (d, 1H);³¹P NMR (CDCl₃) δ−9.49 (p) (rel. to ext. H₃PO₄).

e. 9-(4-Fluorophenylthiophosphoryloxymethylidene)-10-methylacridan,disodium salt (7). With room lighting off, a solution of thebis(cyanoethyl) phosphate compound (0.658 g) in 20 mL of acetone underargon for 30 min. A solution of 116.5 mg of NaOH in 4.0 mL of water wasadded and the solution stirred under argon over night. The precipitatewhich had formed was suction filtered, washed with 100 mL of acetone andair-dried. A second crop of solid formed in the filtrate and wascombined with the first crop. The yield was 0.545 g of 7 as a slightlyyellow solid. ¹H NMR (D₂O) δ3.16 (s, 3H), 6.80-6.98 (m, 4H), 7.06-7.14(m, 4H), 7.21 (t, 1H), 7.32 (t, 1H), 7.78 (d, 1H), 8.19 (d, 1H); ³¹P NMR(D₂O) δ1.22 (s) (rel. to ext. H₃PO₄).

Example 8 Synthesis of Acridan Derivative 8

a. 4′-Methoxyphenyl acridine-9-thiocarboxylate. The Acridine-9-carbonylchloride (2.0 g), made as described above was dissolved in 20 mL ofCH₂Cl₂. 4-Methoxythiophenol (1.27 g) was added dropwise followed by 1.96g of pyridine. The reaction mixture was stirred for 3.5 days at roomtemperature. The precipitate was collected, washed with water and driedto produce a first crop of product. The CH₂Cl₂ solution was washed with3×50 mL of water, dried and evaporated to obtain a crude material whichwas chromatographed on silica gel (ethyl acetate) to yield a second cropof the pure product. ¹H NMR (CDCl₃) δ3.86 (s, 3H), 7.01 (d, 1H), 7.56(d, 2H), 7.62-8.28 (m, 8H).

b. 4′-Methoxyphenyl acridan-9-thiocarboxylate. 4′-Methoxyphenylacridine-9-thiocarboxylate (2.0 g) was suspended in 2-propanol (150 mL).NH₄Cl (7.35 g) was added by portions to the solution followed by zinc(8.9 g). The solution was stirred at room temperature for 2 h and thenwarmed gently for 3 h. TLC of the reaction mixture showed completeconsumption of the starting material. The solution was filtered andprecipitate was washed with CH₂Cl₂. The filtrate and washings wereconcentrated to obtain a crude product which was redissolved in CH₂Cl₂and washed with water (3×50 mL). The organic layer was dried andconcentrated to yield the product which contained a small amount of theacridan isopropyl ester. ¹H NMR (CDCl₃) δ3.74 (s, 3H), 5.19 (s, 1H),6.29 (br s, 1H), 6.75-7.31 (m, 12H).

c. 4′-Methoxyphenyl 10-methylacridan-9-thiocarboxylatetrifluoromethanesulfonate. 4′-Methoxyphenyl acridan-9-thiocarboxylate(1.8 g) was dissolved in CH₂Cl₂ under argon and methyl triflate (6.3 g)was added. The solution was stirred overnight at room temperature toeffect complete methylation. The reaction mixture was concentrated andthe residue separated by column chromatography (30% ethylacetate/hexane) to obtain the 1.08 g of the product. ¹H NMR (CDCl₃)δ3.45 (s, 3H), 3.76 (s, 3H), 5.07 (br s, 1H), 6.81-7.36 (m, 12H).

d. 9-(4-Methoxyphenylthiophosphoryloxymethylidene)-10-methylacridan,bis(cyanoethyl) ester. A solution of 4-methoxyphenyl10-methylacridan-9-thiocarboxylate (700 mg) in 10 mL of dry THF wasadded dropwise to a solution of LDA (1.4 eq.) in 10 mL of dry THFmaintained at −78 C. After stirring for 1 h at −78 C., a solution ofPOCl₃ (520 mg) and pyridine (1.64 g) in 4 mL of THF was added dropwise.Stirring continued for 30 min at −78° C., the dry ice bath was removedand stirring continued for another hour. The solution was again cooledin an ice bath and pyridine (1 mL) and 3-hydroxypropionitrile (0.86 mL)added dropwise. After stirring over night at room temperature, theprecipitated pyridine-HCl was filtered away and the reaction solventevaporated in vacuo. The residue was taken up in ethyl acetate andwashed with water (3×25 mL). The organic solution was dried andconcentrated, the crude product subjected to column chromatography(30-100% ethyl acetate/hexane) from which the product was isolated as alight yellow solid; ¹H NMR (CDCl₃) δ2.44-2.62 (m, 4H), 3.51 (s, 3H),3.82 (s, 3H), 3.88-4.11 (m, 4H), 6.53-7.41 (m, 10H), 7.84-7.91 (m, 2H);³¹P NMR (CDCl₃) δ−9.63 (p) (rel. to ext. H₃PO₄ ).

e. 9-(4-Methoxyphenylthiophosphoryloxymethylidene)-10-methylacridan,disodium salt (8). A solution of the bis(cyanoethyl) phosphate compound(0.42 g) in 11 mL of acetone was purged with argon. A 614 μL portion ofa 2.5 M NaOH solution in water was added dropwise and the solutionstirred under argon over night. The precipitate which had formed wassuction filtered and air-dried producing a quantitative yield of 8 as aslightly yellow solid. ¹H NMR (D₂O) δ3.32 (s, 3H), 3.70 (s, 3H),6.69-7.33 (m, 10H), 7.80 (d, 1H), 8.18 (d, 1H).

Example 9 Synthesis of Acridan Derivative 9

a. 2′,6′-Dimethylphenyl acridine-9-thiocarboxylate.Acridine-9-carboxylic acid (2 g) was suspended in thionyl chloride (25mL) and the reaction mixture was refluxed for 2.5 h. The solvent wasremoved under reduced pressure leaving a solid which was dissolved in 50mL of CH₂Cl₂. This solution was cooled in an ice bath and2,6-dimethylthiophenol (1.23 g) was added dropwise followed by 3.6 mL ofpyridine. The reddish brown reaction mixture was stirred for 1.5 h atroom temperature. The reaction mixture was diluted with CH₂Cl₂ andwashed with 3×50 mL of water. The organic layer was dried andconcentrated to obtain an orange product which was chromatographed onsilica gel (ethyl acetate) to yield 2.5 g of the pure product as anoff-white solid. ¹H NMR (CDCl₃) δ2.68 (s, 6H), 7.30-7.41 (m, 3H),7.63-8.31 (m, 8H).

b. 2′,6′-Dimethylphenyl acridan-9-thiocarboxylate. 2′,6′-Dimethylphenylacridine-9-thiocarboxylate (2.46 g) was suspended in 2-propanol (200mL). Ammonium chloride (9.5 g) was added by portions to the solutionfollowed by zinc (11.65 g).The solution was gently warmed for 2 h. TLCof the reaction mixture showed complete consumption of startingmaterial. The solution was filtered and precipitate was washed withCH₂Cl₂. The filtrate was concentrated to obtain a white solid which wasredissolved in CH₂Cl₂ and washed with water (3×50 mL). The organic layerwas dried over Na₂SO₄ and concentrated to yield 2.46 g of the product asa white solid. ¹H NMR (CDCl₃) δ2.08 (s, 6H), 5.24 (s, 1H), 6.27 (br s,1H), 6.78-7.31 (m, 11H).

c. 2′,6′-Dimethylphenyl 10-methylacridanthiocarboxylate.2′,6′-Dimethylphenyl 10-methylacridan-9-thiocarboxylate (2.0 g)dissolved in 30 mL of CH₂Cl₂ under argon and methyl triflate (6.6 mL)was added. The solution was stirred for 3 days at room temperature. Themixture was evaporated to dryness and the crude product purified bycolumn chromatography (CH₂Cl₂) to obtain 1.85 g of the product as awhite solid. ¹H NMR (CDCl₃) δ2.09 (s, 6H), 3.46 (s, 3H), 5.09 (s, 1H),6.97-7.36 (m, 11H).

d. 9-(2,6-Dimethylphenylthiophosphoryloxymethylidene)-10-methylacridan,bis(cyanoethyl) ester. 2,6-Dimethylphenyl10-methylacridan-9-thiocarboxylate (700 mg) in 12 mL of dry THF wasadded to a solution of LDA (1.4 eq.) in 10 mL of dry THF at −78° C. Theorange solution was stirred for 60 min at −78 C. A solution of POCl₃(280 μL) and pyridine (1.57 mL) in 4 mL of THF was added dropwise. Thereaction mixture was stirred for 15 min before the dry ice bath wasremoved. Stirring continued for 60 min. TLC (30% ethyl acetate/hexane)showed that most of the starting material was reacted.

The solution was cooled in an ice bath and treated with pyridine (1.0mL) and 3-hydroxypropionitrile (666 μL). After stirring over night atroom temperature, the precipitated pyridine-HCl was filtered and washedwith THF. The combined organic solutions were evaporated in vacuo. Theorganic layer was dried and concentrated to obtain an orange productwhich was chromatographed on silica gel (ethyl acetate) to yield 80 mgof the pure product as a yellow oil. ¹H NMR (CDCl₃) δ2.34-2.43 (m, 4H),2.47 (s, 6H), 3.47 (s, 3H), 3.42-3.71 (m, 4H), 7.01-8.07 (m, 11H); ³¹PNMR (CDCl₃) δ−10.207 (p) (rel. to ext. H₃PO₄).

e. 9-(2,6-Dimethylphenylthiophosphoryloxymethylidene)-10-methylacridan.disodium salt (9). A solution of the bis(cyanoethyl) phosphate compound(0.80 g) in 6 mL of acetone was purged with argon. A solution of 1M NaOHin water (293 μL) was added dropwise followed by an additional 300 μL ofwater and the solution stirred under argon over night. The precipitatewhich had formed was suction filtered, washed with acetone andair-dried. The yield was 0.60 g of 9 as a white solid. ¹H NMR (D₂O)δ2.13 (s, 6H), 3.19 (s, 3H), 6.60-8.19 (m, 11H); ³¹P NMR (D₂O) δ1.653(s) (rel. to ext. H₃PO₄).

Example 10 Synthesis of Acridan Derivative 10

a. 4-Fluoroacetanilide. 4-Fluoroaniline (20 g) was dissolved in 25 mL ofacetic acid and cooled in an ice bath. Acetic anhydride (25 mL) wasadded in 5 mL portions to the stirred solution. The resulting solutionwas poured into 200 mL of cold water and the precipitated productfiltered off. The solid was washed with water and vacuum-dried. ¹H NMR(CDCl₃) δ2.175 (s, 3H), 7.014 (t, 2H), 7.15 (br s, 1H), 7.43-7.48 (m,2H).

b. 4,4′-Difluorodiphenylamine. 4-Fluoroacetanilide (12.0 g) wascondensed with 1-bromo-4-fluorobenzene (21 mL) in the presence of 11.08g of K₂CO₃ and 1.61 g of CuI at 190° C. for 90 h. After cooling, themixture was filtered and the solid washed with CH₂Cl₂. The combinedorganic solutions were evaporated under vacuum producing ca. 20 g of adark brown liquid. This was dissolved in 100 mL of ethanol and refluxedwith 9 g of KOH for 24 h. The ethanol was evaporated and the darkresidue taken up in ether and washed with water (3×100 mL). The ethersolution was dried and concentrated and the crude product purified bycolumn chromatography on silica using 15% ethyl acetate/hexane: ¹H NMR(CDCl₃) δ5.46 (br s, 1H), 6.947 (s, 4H), 6.97 (s, 4H); ¹³C NMR (CDCl₃)δ115.86, 116.16, 119.38, 119.47.

c. 2,7-Difluoroacridine-9-carboxylic acid. 4,4′-Difluorodiphenylamine(5.4 g) dissolved in 50 mL of CH₂Cl₂ was added to a solution of 2.52 mL(0.11 mol) of oxalyl chloride in 30 mL of CH₂Cl₂ under an argonatmosphere at a rate to maintain reflux. The mixture was refluxed anadditional 35 min. The resulting solution was evaporated to removeexcess oxalyl chloride. The solid was redissolved in 75 mL of CH₂Cl₂ andcooled in an ice bath. The flask was purged with argon and AlCl₃ (14.28g) was added in portions while the mixture was stirred. The mixturebecame thick during the addition and began to reflux. Reflux wasmaintained for an additional hour after all of the AlCl₃ had been added.The cooled mixture was evaporated in vacuo and quenched with 300 mL of3:1 ice/5 M HCl. The mixture was stirred for 1 h, the orange solid(isatin) filtered off with suction and washed with water. ¹H NMR(acetone-d₆) δ6.92-6.97 (m, 1H), 7.35-7.61 (m, 6H).

The isatin product was refluxed in 110 mL of 10% KOH solution in waterover night. The dark green mixture was cooled and acidified with 400 mLof 1:1 ice/5 M HCl. The solid was washed with water and air-driedyielding the acridine acid. ¹H NMR (DMSO-d₆) δ7.81-7.94 (m, 4H),8.31-8.36 (m, 2H).

d. Phenyl 2,7-difluoroacridine-9-thiocarboxylate.2,7-Difluoroacridine-9-carboxylic acid (1.0 g) was suspended in SOCl₂ (5mL) and the reaction mixture was refluxed for 3 h. The solvent wasremoved under reduced pressure leaving a brown solid which was dissolvedin 20 mL of CH₂Cl₂ under argon. Thiophenol (468 mg) was added followedby pyridine (2 mL). The reaction mixture was stirred overnight at roomtemperature. The reaction mixture was diluted with CH₂C₂ and washed withwater (3×50 mL). The organic layer was dried over MgSO₄ and concentratedto obtain a crude material which was chromatographed on silica gel (40%ethyl acetate/hexane) to yield 1.2 g of the pure product. ¹H NMR (CDCl₃)δ7.52-7.75 (m, 9H), 8.26-8.30 (m, 2H).

e. Phenyl 2,7-difluoroacridan-9-thiocarboxylate. Phenyl2,7-difluoroacridine-9-thiocarboxylate (1.2 g) was suspended in2-propanol (125 mL) along with NH₄Cl (4.57 g). Zinc (5.5 g) was addedand the reaction mixture was warmed for 2.5 h followed by a 1.5 h periodat room temperature. TLC of the reaction mixture showed completeconversion to a new material. The solution was filtered and theprecipitate was washed with CH₂Cl₂. The filtrate was concentrated andthe light orange residue was redissolved in CH₂Cl₂ and washed with water(2×100 mL). The organic layer was dried over Na₂SO₄ and concentrated toyield the crude product which was used without further purification. ¹HNMR (CDCl₃) δ5.12 (s, 1H), 6.19 (br s, 1H), 6.72-7.35 (m, 11H).

f. Phenyl 2,7-difluoro-10-methylacridan-9-thiocarboxylate. Phenyl2,7-difluoroacridan-9-thiocarboxylate (1.4 g) was dissolved in CH₂Cl₂(50 mL) under argon and methyl trifluoromethanesulfonate (5.29 g) wasadded. The solution was stirred overnight at room temperature. TLCshowed the conversion to be ca. 50% complete so another 2 mL of methyltriflate was added and stirring continued for another 40 h. Thisreaction mixture was concentrated and the residue separatedchromatographically using 20-50% CH₂Cl₂/hexane to obtain the productalong with a minor amount of the isopropyl ester of theacridancarboxylate as a by-product. 1H NMR (acetone-d₆) δ3.41 (s, 3H),4.98 (s, 1H), 6.89-7.34 (m, 11H).

g. 9-(Phenylthiophosphoryloxymethylidene)-2,7-difluoro-10-methylacridan,bis(cyanoethyl) ester. Phenyl2,7-difluoro-10-methylacridan-9-thiocarboxylate (500 mg, 1.3 mmol) wasadded to a solution of LDA (1.4 mmol) in THF −78° C. After stirring 1 h,a solution of POCl₃ (313 mg) and pyridine (1.07 g) in 4 mL of THF wasadded and the reaction mixture maintained at −78° C. for 1 h. The dryice bath was removed and stirring continued for 1 h.

The solution was cooled in an ice bath and treated dropwise withpyridine and 3-hydroxypropionitrile (484 mg) in 4 mL of THF. Afterstirring over night at room temperature, the precipitated pyridine-HClwas filtered away and the reaction solvent evaporated in vacuo. Theresidue was taken up in ethyl acetate and washed with 4×25 mL of water.After drying and evaporating the ethyl acetate, the residue wasseparated chromatographically (75-80% ethyl acetate/hexane) to yield theproduct was isolated; ¹H NMR (CDCl₃) δ2.48-2.65 (m, 4H), 3.48 (s, 3H),4.02-4.16 (m, 4H), 6.91-7.66 (m, 11H); ³¹P NMR (CDCl₃) δ−9.874 (p) (rel.to ext. H₃PO₄).

h. 9-(Phenylthiophosphoryloxymethylidene)-2,7-difluoro-10-methylacridan,disodium salt (10). A solution of the bis(cyanoethyl) phosphate compound(0.28 g) in 17 mL of acetone was cooled in an ice bath and purged withargon. A solution of 1N NaOH in 1.02 mL of water was added dropwise andthe solution stirred under argon for 16 h. The precipitate which hadformed was suction filtered, washed with acetone and vacuum-dried. Theyield was 0.236 g of 10 as an off-white solid. ¹H NMR (D₂O) δ3.28 (s,3H), 6.78-8.21 (m, 11H); ³¹P NMR (D₂O) δ1.006 (s) (rel. to ext. H₃PO₄).

Example 11 Synthesis of Acridan Derivative 11

a. 2′,2′,2′-Trifluoroethyl acridine-9-thiocarboxylate.Acridine-9-carbonyl chloride (1.89 g), made as described above wasdissolved in 30 mL of CH₂Cl₂ under argon. This solution was cooled in anice bath and 2,2,2-trifluoroethanethiol (1.0) was added dropwisefollowed by 3.23 g of pyridine. The reaction mixture was stirred at roomtemperature for 3 days. Water (20 mL) was added and the remainingprecipitate filtered and discarded. The CH₂Cl₂ solution was washed with3×25 mL of water, dried and evaporated to obtain the product as anoff-white solid sufficiently pure to take on to the next reaction. ¹HNMR (CDCl₃) δ4.02-4.10 (q, 2H), 7.61-8.31 (m, 8H).

b. 2′,2′,2′-Trifluoroethyl acridan-9-thiocarboxylate.2′,2′,2′-Trifluoroethyl acridine-9-thiocarboxylate (1.7 g) was suspendedin 2-propanol (150 mL) along with NH₄Cl (7.08 g). Zinc (8.61 g) wasadded and the reaction mixture was stirred for 1.5 h at roomtemperature. TLC of the reaction mixture showed complete conversion to anew material. The solution was filtered and the precipitate was washedwith CH₂Cl₂. The filtrate was concentrated and the light orange residuewas redissolved in CH₂Cl₂ and washed with water (3×50 mL). The organiclayer was dried and concentrated to yield the crude product as anoff-white solid sufficiently pure to take on to the next reaction. ¹HNMR (CDCl₃) δ3.37-3.47 (q, 2H), 5.206 (s, 1H), 6.27 (br s, 1H),6.78-7.27 (m, 8H).

c. 2′,2′,2′-Trifluoroethyl 10-methylacridan-9-thiocarboxylate.2′,2′,2′-Trifluoroethyl acridan-9-thiocarboxylate (1.66 g) was dissolvedin CH₂Cl₂ (20 mL) under argon and methyl triflate (4.06 mL) was added.The brown solution was stirred for 1.5 days at room temperature. Afterconcentrating the CH₂Cl₂, the crude product was purified by columnchromatography using 50% CH₂Cl₂/hexane. ¹H NMR (CDCl₃) δ3.39-3.43 (q,2H), 3.43 (s, 3H), 5.04 (s, 1H), 6.98-7.38 (m, 8H).

d. 9-(2′,2′,2′-Trifluoroethylthiophosphoryloxymethylidene)-10-methylacridan, bis(cyanoethyl) ester. 2′,2′,2′-Trifluoroethyl10-methylacridan-9-thiocarboxylate (300 mg) in 10 mL of THF was added toa solution of LDA (1.4 eq.) in 10 mL of THF dropwise at −78° C. Afterstirring 60 min at −78 C., a solution of POCl₃ (239 mg) and pyridine(703 mg) in 4 mL of THF was added slowly. After 30 min, the dry ice bathwas removed and stirring continued for 60 min. The solution was cooledin an ice bath and treated with pyridine (500 μL) and3-hydroxypropionitrile (395 μL). A brownish-yellow precipitate formed.After stirring over night at room temperature, the precipitate wasfiltered away and the reaction solvent evaporated in vacuo. The residuewas taken up in ethyl acetate, washed with 5×25 mL of water, dried andconcentrated. The crude product was separated chromatographically usingCH₂Cl₂ to elute the column and then switching solvents to a 60-100%ethyl acetate/hexane gradient. Two fractions were isolated, each asmixture of two closely eluting products, the slower eluting being theminor component. Each fraction was further purified separately by prep.TLC using 25% ethyl acetate/hexane. The slower eluting product proved tobe the expected bis(cyanoethyl)phosphate ester. ¹H NMR (CDCl₃) δ2.69 (t,4H), 3.41-3.54 (q, 2H), 3.49 (s, 3H), 4.04-4.24 (m, 4H), 7.04-7.95 (m,8H); ³¹p NMR-8.66 (p).

The other product was determined by ¹H NMR, ¹³C NMR, ¹⁹F NMR and ³¹P NMRas well as homonuclear and heteronuclear decoupling experiments to be9-(2′,2′-difluoroethenylthio-phosphoryloxymethylidene)-10-methylacridan,bis(cyanoethyl) ester, derived from elimination of HF from the SCH₂CF₃group and phosphorylation of the enolate. ¹H NMR (CDCl₃) δ2.60-2.76 (m,4H), 3.49 (s, 3H), 4.02-4.26 (m, 4H), 5.17 (d, 1H), 7.03-7.88 (m, 8H);¹⁹F NMR (CDCl₃) δ−76.76 (d, J=Hz), −78.88 (t, J=Hz); ³¹P NMR (CDCl₃)δ−8.83 (p). Irradiation of the doublet at δ5.17 did not affect any othersignal in the ¹H NMR spectrum. Irradiation of the multiplet atδ4.02-4.26 collapsed the multiplet at δ2.60-2.76 to a singlet andcollapsed the phosphorus signal to a singlet. Irradiation of the doubletat δ5.17 in the ¹H spectrum collapsed the triplet in the ¹⁹F spectrum toa doublet.

e.9-(2′,2′,2′-Trifluoroethylthiophosphoryloxymethylidene)-10-methylacridan,disodium salt (11). A solution of the bis(cyanoethyl) phosphate compound(15 mg) in 4 mL of acetone was purged with argon. A solution of 1M NaOHin water (58 μL) was added dropwise followed by an additional 100 μL ofwater and the solution stirred under argon over night. TLC showedcomplete deprotection. The mixture was concentrated to dryness,producing an off-white solid which was washed with 20% CH₂Cl₂/acetoneand air-dried. ¹H NMR (D₂O) δ3.399 (s, 3H), 3.45-3.61 (m, 2H), 7.04-8.18(m, 8H); ³¹P NMR (D₂O) δ1.465 (s) (rel. to ext. H₃PO₄).

Example 12 Synthesis of Acridan Derivative 12

a. 4′-Chlorophenyl acridine-9-thiocarboxylate. 4-Chloro-thiophenol (4.75g) and 7.22 g of acridine-9-carbonyl chloride were dissolved in 100 mLof CH₂Cl₂ followed by 12.1 mL of pyridine. The reaction mixture becameorange-brown. The mixture was stirred overnight at room temperatureunder argon. After evaporation of is 15 solvent, the solids were washedwith 100 mL of hexanes, filtered, washed with another 100 mL of hexanes,filtered, and then with a 500 mL of water, filtered and air-dried. Thethioester was obtained (8.71 g) as a slightly brownish yellow solid. ¹HNMR (CDCl₃) δ7.47-7.50 (m, 2H), 7.58-7.67 (m, 4H), 7.81-7.86 (m, 2H),8.12 (d, 2H), 8.29 (d, 2H).

b. 4′-Chlorophenyl acridan-9-thiocarboxylate. 4′-Chlorophenylacridine-9-thiocarboxylate (2.0 g) was dissolved in CH₂Cl₂ (25 mL). Thesolution was purged with argon and then 3.72 g of zinc powder addedfollowed by 0.45 mL of acetic acid. TLC showed the starting material wasconsumed in 20 min. The mixture was filtered and the solids washed withCH₂Cl₂. The combined CH₂Cl₂ solutions were washed with water (3×50 mL)and dried. A small amount of the product was purified by prep. TLC foranalytical characterization. the remainder of the product was usedwithout further purification. ¹H NMR (CDCl₃) δ5.22 (s, 1H), 6.28 (s,1H), 6.79-7.31 (m, 12H).

c. 4′-Chlorophenyl 10-methylacridan-9-thiocarboxylate. 4′-Chlorophenylacridan-9-thiocarboxylate (2.0 g) was dissolved in CH₂Cl₂ (30 mL) underargon and methyl triflate (6.5 g) was added. The brown solution wasevaporated and the crude product purified by column chromatography using30% ethyl acetate/hexanes. The pure product (1.8 g) was therebyobtained. ¹H NMR (CDCl₃) δ3.47 (s, 3H), 5.09 (s, 1H), 7.02-7.39 (m,12H).

d. 9-(4-Chlorophenylthiophosphoryloxymethylidene)-10-methylacridan,bis(cyanoethyl) ester. 4-Chlorophenyl 10-methylacridan-9-thiocarboxylate(0.70 g) in 10 mL of anhydrous THF was added dropwise to a solution ofLDA (1.4 eq.) in THF at −78 C. After stirring 60 min at −78 C., theyellow solution was treated with a solution of POCl₃ (0.517 g) andpyridine (1.52 mL) in 4 mL of THF slowly. The dry ice bath was removedafter 30 min and stirring continued for 1 h. The solution became yellowand formed a precipitate.

The mixture was cooled in an ice bath and treated with3-hydroxypropionitrile (0.89 g) and 1.0 mL of pyridine. The ice bathremoved after the addition was complete. After stirring over night atroom temperature, the precipitated pyridine-HCl was filtered off andwashed with THF. The combined filtrates were evaporated in vacuo and thebrown material obtained was dissolved in ethyl acetate and washed with4×25 mL of water. The ethyl acetate solution was dried and concentrated.The residue was separated by column chromatography using 80-100% ethylacetate/hexanes from which the 0.325 g of the product was isolated; ¹HNMR (CDCl₃) δ2.48-2.64 (m, 4H), 3.53 (s, 3H), 3.86-4.16 (m, 4H),6.94-7.94 (m, 12H); ³¹P NMR (D₂O) δ−9.48 (p) (rel. to ext. H₃PO₄).

e. 9-(4-Chlorophenylthiophosphoryloxymethylidene)-10-methylacridan,disodium salt (12). A solution of the bis(cyanoethyl) phosphate compound(0.325 g) in 10 mL of acetone was purged with argon. A solution of 2.5 MNaOH (473 μL) was added followed by an additional 500 μL of water. Thesolution was stirred under argon over night. The precipitate which hadformed was suction filtered and air-dried. The mother liquor was foundto contain the mono(cyanoethyl)-protected compound (140 mg). A secondcrop of the disodium salt was obtained by repeating the NaOHdeprotection. ¹H NMR (D₂O) δ3.35 (s, 3H), 6.92-7.36 (m, 10H), 7.78 (d,1H), 8.20 (d, 1H); ³¹P NMR (D₂O) δ1.22 (s) (rel. to ext. H₃ PO₄).

Example 13 Synthesis of Acridan Derivative 13

a. Naphthyl acridine-9-thiocarboxylate. 2-Naphthalenethiol (48.81 g) andthe acridine-9-carbonyl chloride prepared from 65.17 g ofacridine-9-carboxylic acid were dissolved in 100 mL of CH₂Cl₂ followedby the addition of 120 mL of pyridine. The mixture was stirred overnightat room temperature under argon. After evaporation of solvent, thesolids were washed with 500 mL of hexanes, filtered, washed with another500 mL of hexanes, filtered, and then washed with 600 mL of water,filtered and air-dried overnight. The thioester was dissolved in 1500 mlof CH₂Cl₂, dried over sodium sulfate, filtered, and dried in vacuo. Thethioester was obtained (94.67 g) as a brown solid. ¹H NMR (CDCl₃)δ7.54-8.00 (m, 11H), 8.17-8.31 (m, 4H).

b. Naphthyl 10-methylacridinium-9-thiocarboxylate triflate. Naphthylacridine-9-thiocarboxylate (26.38 g) was suspended in CH₂Cl₂ (200 mL).Methyl trifluoromethanesulfonate (24.5 ml) was added and the mixtureleft to stir overnight. The mixture was filtered and the solids washedwith CH₂Cl₂ (300 ml) and hexanes (500 ml). After air drying, the product(28.83 g) was obtained as a yellow solid. ¹H NMR (acetone-d₆) δ5.20 (S,3H), 7.66-7.75 (m, 2H), 7.88-7.92 (m, 1H), 8.03-8.09 (m, 2H), 8.15 (d,1H), 8.26 (t, 2H), 8.48 (S, 1H), 8.61-8.68 (m, 2H), 8.80 (d, 2H), 9.03(d, 2H).

c. Naphthyl 10-methylacridan-9-thiocarboxylate. Naphthyl10-methylacridinium-9-thiocarboxylate triflate (65.50 g) was suspendedin CH₂Cl₂ (1000 mL) under argon and glacial acetic acid (21.2 ml) andzinc (40.43 g) were added. After stirring overnight, TLC showed thedissappearance of the starting material and the formation of a newproduct. The reaction mixture was filtered through a bed of silica geland the CH₂Cl₂ removed in vacuo. The slightly yellow solid obtained wasstirred in isopropanol (500 ml), filtered, washed with 500 ml moreisopropanol, and allowed to air dry. The pure product (46.36 g) wasthereby obtained. ¹H NMR (CDCl₃) δ3.47 (s, 3H), 5.13 (s, 1H), 7.00-7.06(m, 4H), 7.25-7.49 (m, 7H), 7.70-7.79 (m, 4H).

d. 9-(Naphthylthiophosphoryloxymethylidene)-10-methyl-acridan,bis(cyanoethyl) ester. Naphthyl 10-methylacridan-9-thiocarboxylate(17.32 g) in 600 mL of anhydrous THF was added dropwise to a solution ofLDA (1.25 eq.) in THF at −78 C. After stirring 90 min at −78 C., theorangish brown solution was treated with a solution of POCl₃ (20.80 g)and pyridine (50 mL) in 150 mL of THF slowly. The dry ice bath wasremoved after 60 min and stirring continued for 1 h. The solution becamebrown and formed a precipitate.

The mixture was treated with 3-hydroxypropionitrile (27.8 ml). Afterstirring over night at room temperature, the precipitated pyridine-HClwas filtered off and washed with THF. The combined filtrates wereevaporated in vacuo and the brown oil obtained was separated by columnchromatography using 50-100% ethyl acetate/hexanes from which theproduct was isolated. The yellow oil was dissolved in CH₂Cl₂ (300 ml),washed with water (450 ml), dried over sodium sulfate, filtered, anddried in vacuo. This yielded the product (17.76 g) as a yellow solid. ¹HNMR (CDCl₃) δ2.33-2.53 (m, 4H), 3.53 (s, 3H), 3.82-4.06 (m, 4H), 6.93(t, 1H), 7.03 (d, 1H), 7.10-7.18 (m, 2H), 7.25-7.55 (m, 5H), 7.79-7.92(m, 5H), 8.02 (d, 1H); ³¹P NNR (CDCl₃) δ−9.69 (p) (rel. to ext. H₃PO₄).

e. 9-(Naphthylthiophosphoryloxymethylidene)-10-methylacridan, disodiumsalt (13). A solution of the bis(cyanoethyl) phosphate compound (17.28g) in 200 mL of acetone was purged with argon. A solution of NaOH (2.76g) in 50 ml of water was added and the solution was stirred under argonover night. The precipitate which had formed was suction filtered washedwith 20% water in acetone (300 ml) and dried under vacuum. The product(15.07 g) was obtained as a light yellow solid. ¹H NMR (D₂O) δ3.22 (s,3H), 6.67 (d, 1H), 6.87 (t, 1H), 7.01 (t, 1H), 7.08-7.15 (m, 2H), 7.23(d, 1H), 7.31-44 (m, 3H), 7.51 (s, 1H), 7.59 (d, 2H), 7.73 (d, 1H), 7.86(d, 1H), 8.25 (d, 1H); ³¹P NM (D₂O) δ1.30 (s) (rel. to ext. H₃PO₄).

Example 14 Chemiluminescent Detection of Alkaline Phosphatase withCompound 1

An effective reagent composition for chemiluminescent detection ofalkaline phosphatase comprised 0.1 M tris buffer, pH 8.5, 0.88 mmmagnesium salt, 0.33 mM acridan phosphate 1 (from a 1:100 dilution of a0.033 M methanol solution) and 0.01 mg/mL of the Enhancer A(polyvinylbenzyltributylphosphonium chlorideco-polyvinylbenzyltrioctylphosphonium chloride, containing a 3:1 ratioof tributyl:trioctyl groups). Reaction of 100 μL of this compositionwith 10⁻¹³ mol of AP at 25° C. in a test tube housed in a Turner TD-20eluminometer produced easily measurable blue chemiluminescence whichreached maximum intensity in 2 min.

Example 15 Chemiluminescent Detection with Compounds 2-13

In the manner of Example 14, compositions containing each of compounds2-13 were reacted with AP at 25° C. Each produced easily measurablechemiluminescence discernable above the background measured in theabsence of AP.

It will be obvious to one skilled in the art that other compounds offormula I in addition to those specifically illustrated herein willfunction in like manner in the present methods.

Example 16 Chemiluminescent Detection of Alkaline Phosphatase withCompound 5

An effective reagent composition for chemiluminescent detection ofalkaline phosphatase comprised 0.2 M 2-methyl-2-amino-1-propanol buffer,pH 9.6, 0.88 mm Mg²⁺, 0.66 mM acridan phosphate 5 (from a 1:100 dilutionof a 0.033 M methanol solution) and 0.5 mg/mL of the Enhancer A.Reaction of 100 μL of this composition with 10⁻¹³ mol of AP at 25° C. ina test tube housed in a Turner TD-20e luminometer produced easilymeasurable blue chemiluminescence which reached maximum intensity in 2min. Light intensity measured between 1 and 10 min correlated withamount of enzyme in the range 8×10⁻¹⁴ mol to 8×10⁻¹⁸ mol.

Example 17 Kinetic Profile of Chemiluminescence Intensity

The rapid detection speed afforded by compositions containing theacridan phosphate 1 is shown by the plot in FIG. 1. Reaction of 100 μLof the reagent composition of Example 14 with 8×10⁻¹⁶ mol of AP at 25°C. caused a burst of light emission which achieved maximum intensity inca. 2 min. The figure also shows for comparison the chemiluminescenceprofile of the ester phenyl 10-methylacridan-9-carboxylate in a reagentcomposition similar to that described in Example 14 but containing theester in place of 1. Addition of AP to the latter solution of the esterproduced no effect. The much lower light intensity and slower rise timefrom spontaneous autoxidation of the ester is incompatible with a schemein which emission from reaction of 1 is simply due to generation of theester (via removal of the phosphate protecting group from the enolphosphate) by AP followed by autoxidation of the ester.

Example 18 Spectroscopic Study of Reaction of 1 with AP

The progress of the reaction between 3 mL of the reagent composition ofExample 14 and 2.4×10⁻¹² mol of AP at ambient temperature was monitoredby UV-visible spectroscopy with a diode array detector. The spectrum wasacquired at 5 min intervals. The evolution of the spectrum revealed inFIG. 2 showed a complex pattern consisting of multiple intermediates andproducts. Curves labeled A-F represent scans taken 0, 5, 10, 20, 40 and60 min after addition of enzyme.

Example 19 Chemiluminescence Spectrum

A chemiluminescence spectrum was obtained using a device constructed byDr. Barry Schoenfelner of Lumigen. The reagent composition of Example 14(200 μL) was reacted with AP (8×10⁻¹³ mol) in a sample holder consistingof a test tube inside a light tight box. The emitted light was collectedby a lens, and dispersed by a grating monochromator onto a CCD cameraelement. No correction for the change in intensity with time is requiredsince this system images all wavelengths of visible lightsimultaneously. The spectrum of light emitted, shown in FIG. 3, revealsa broad emission with a maximum intensity at about 430 nm. This spectrummatches the fluorescence of N-methylacridone. The apparent finestructure in the spectrum is the result of instrument noise.

Example 20 Effect of pH on Chemiluminescent Reaction of 1 with AlkalinePhosphatase

Chemiluminescent detection of alkaline phosphatase with acridans of thepresent invention can be performed over a broad range of pH. Solutionscomprising a 0.1 M buffer (either tris or 2-methyl-2-amino-1-propanol,221), pH 7-10.5, 0.88 mM Mg²⁺, 0.33 mM acridan phosphate 1 (from a 1:100dilution of a 0.033 M methanol solution) and 0.01 mg/mL of Enhancer Awere prepared and the background light emission measured after 10 min at25° C. An aliquot of an AP solution containing 8×10⁻¹⁶ mol of enzyme wasinjected and light intensity monitored until maximum intensity wasreached. S/B represents the ratio of maximum light intensity to thelight intensity in the absence of enzyme.

TABLE 2 Entry pH Buffer S/B 1 7.0 tris 37 2 7.5 tris 144 3 8.0 tris 2734 8.5 tris 280 5 9.0 tris 195 6 9.0 221 200 7 9.5 221 87 8 10.0 221 13 910.5 221 1.3

Example 21 Enhancement of Chemiluminescence by Surfactants

The enhancement of chemiluminescence, defined as the increase in lightintensity over the level in the absence of the test substance, wasassessed under a standard set of test conditions in the reaction ofacridan 1 with AP in the presence of various surfactant compounds. Theconcentration of each surfactant producing the greatest enhancement wasdetermined independently. The value in the column marked S/B representsthe ratio of light intensities with 10⁻¹⁶ mol of AP and that with noenzyme. The column marked Rel. presents the same ratio normalized to theresults obtained with no enhancer (entry 11).

TABLE 3 Entry Surfactant Concentration S/B Rel. 1 A 0.01 g/L 562 40.1 2B 0.01 431 30.8 3 C 0.01 389 27.8 4 D 0.25 295 21.1 5 E 0.10 162 11.6 6F 0.05 120 8.6 7 G 0.10 63 4.5 8 H 0.10 26 1.9 9 I 0.43 24 1.7 10 J 0.1017 1.2 11 None — 14 1 * Measured at 2 min. A:poly(vinylbenzyltributylphosphoniumchloride)-co-poly-(vinylbenzyltrioctylphosphonium chloride) (3:1 ratioof tributyl:trioctyl groups B: polyvinylbenzylbenzyldimethylammoniumchloride C: poly(vinylbenzyltributylphosphoniumchloride)-co-poly-(vinylbenzyltrioctylphosphonium chloride)-co-poly(vinyl-benzylfluorescein) (75:25:1) D:poly(vinylbenzyltributylphosphonium chloride) E:1-trioctylphosphoniummethyl-4-tributylphosphonium-methylbenzenedichloride F: Tween ™ 20, polyoxyethylene(20)sorbitan monolaurate G:1-trioctylphosphoniummethyl-4-tributylammonium-methylbenzene, mixedbromide chloride salt H: SDS, sodium dodecyl sulfate I: CTAB,cetyltrimethylammonium bromide J:1-trioctylammoniumnmethyl-4-tributylammoniummethylbenzene dichloride TheS/B values in entries 4-11 do not represent the maximum enhancementobtainable since light intensity continues to rise for >1 hour whenthese enhancers are used.

Example 22 Effect of the Concentration of Enhancer A on Light Intensityand Kinetics with Acridan Phosphate 1

A concentration dependence study was conducted in order to determine theamount of Enhancer A which produced the highest signal/background (S/B)level in the chemiluminescent reaction of acridan phosphate 1 with AP.Solutions of 1 in 0.1 M tris buffer, pH 8.5 containing 0.88 mM Mg²⁺ and0.5, 0.25, 0.1, 0.05 or 0.025 mg/mL of Enhancer A were prepared.Aliquots (100 μL) were equilibrated at 25° C. and reacted with 8×10⁻¹⁶moles of AP. The S/B values reported in Table 4 show that maximum lightenhancement occurs with 0.005-0.01 g/L of enhancer.

TABLE 4 Entry Concentration S/B 2 min S/B 10 min 1 0.0025 g/L 431 262 20.005 714 500 3 0.010 660 562 4 0.025 399 360 5 0.050 247 240 6 0.10 212163 7 0.50  40  84

Example 23 Linearity and Sensitivity of Detection of AlkalinePhosphatase with Acridan Phosphate 1

The sensitivity and linearity of detection of AP was determined using areagent composition of the present invention containing acridanphosphate 1. To each of 3 wells in a 96-well white microplate 10 μLdilutions of AP containing between 8×10⁻¹⁵ mol and 8×10⁻²⁰ mol of enzymewere added. A 100 μL aliquot of detection reagent comprising 0.33 mMsolution acridan phosphate 1 in 0.1 M tris buffer, pH 8.5, 0.88 mMMgCl₂, 0.01 mg/mL of Enhancer A and 1% methanol was injected. Lightintensities were measured after 2.5 min. FIG. 4 shows the lineardetection of alkaline phosphatase. The term S-B refers to thechemiluminescence signal (S) in RLU in the presence of AP corrected forbackground chemiluminescence (B) in the absence of AP. The calculateddetection limit (twice the standard deviation of the background) wasdetermined to be 1.2×10⁻¹⁹ mol under these conditions. A similar resultwas obtained using light intensities measured after 10 min.

Example 24 Chemiluminescent Detection of AP by pH Change

An alternate way to detect the light emitted by reaction of AP with 1 isto incubate a reagent composition containing 1 with AP at a first pH inthe absence of enhancer and then rapidly raise the pH by injecting asolution of a strong base containing enhancer to cause a burst of lightemission. A set of conditions which permitted the detection of <10⁻¹⁸mol of AP was devised.

A reagent composition (100 μL) comprising 0.33 mM acridan phosphate 1 in0.1 M tris buffer, pH 9, 0.88 mM MgCl₂, was reacted with 10 μL of AP(8×10^(−15-8×10) ⁻²⁰ mol) or 10 μL of water as a reagent blank for 4 minat ambient temperature in the wells of a black microplate. A solutioncontaining 0.5 mg/mL of Enhancer A in 1 N NaOH (100 μL) was injected andlight intensity integrated for 10 sec. Light intensity was a linearfunction of the amount of AP between 8×10⁻¹⁵ and 8×10⁻¹⁹ mol of AP asshown in FIG. 5.

Example 25 Chemiluminescent Detection of Acid Phosphatase and Inhibitionby Tartrate

A reagent composition for chemiluminescent detection of acid phosphatase(AcP) comprised 0.1 M tris buffer, pH 7, 0.33 mM acridan phosphate 1(from a 1:100 dilution of a 0.033 M methanol solution) and 0.01-0.1% ofEnhancer A. Reaction of 100 μL of this composition with AcP (Sigma AcPLIN-TROL, reconstituted to 2.0 mL, 83 U/L) at ambient temperature in atest tube housed in a Turner TD-20e luminometer producedchemiluminescence which reached maximum intensity nearly instantaneouslyand remained nearly constant for several minutes. Addition of theprotein bovine serum albumin to the detection reagent at 0.1% prolongedthe duration of light emission significantly.

Addition of 5 μL of 0.04 M tartrate in citrate buffer (0.09 M, pH 4.8)caused complete extinction of light emission due to inhibition of enzymeactivity by tartrate, a specific inhibitor for prostatic acidphosphatase. The quenching of emission was not due to a reduction of thepH since addition of 10 μL of citrate buffer caused only a 25% reductionin light intensity.

Example 26 Chemiluminescent Detection of AcP by pH Change

An alternate way to detect the light emitted by reaction of AcP with 1is to incubate a reagent composition containing 1 and enhancer with AcPat a first pH and then rapidly raise the pH by injecting a solution of astrong base to cause a burst of light emission. A reagent composition(100 μL) comprising 0.33 mM acridan phosphate 1 in 0.1 M tris buffer, pH7.0, 0.1% BSA and 0.01% Enhancer A was reacted with 3 μL of AcP (SigmaAcP LIN-TROL, reconstituted to 2.0 mL, 83 U/L) for 8 min at ambienttemperature in a test tube. A solution of 1 N NaOH (50 μL) was injectedand light intensity integrated for 4 min. Light intensity was threetimes the reagent blank.

Example 27 Western Blot Assay using PVDF Membrane

Compositions of the present invention were used to detect and quantify aprotein, human transferrin in a Western blot with an AP-labeled antibodyon a polyvinylidene difluoride (PVDF) membrane. Dilutions of transferrincontaining from 5000, 1000, 180, 30 and 5 pg, respectively, of proteinwere electrophoresed and transferred to PVDF membranes (Millipore,Bedford, Mass.). The transferrin bands were blocked with and thenreacted sequentially with goat anti-human transferrin and rabbitanti-goat-AP conjugate. The membranes were soaked briefly with reagentscomprising 0.2 M 221 buffer, pH 9.6 containing 0.88 mM MgCl₂, 0.66 mMacridan phosphate 1 and 0.1 to 1 mg/mL of Enhancer A. The membranes wereplaced between transparent plastic sheets and exposed to X-ray film.FIG. 6 demonstrates the detection of human transferrin after 15 min witha 1 min exposure using a reagent composition containing 0.1 mg/mL ofenhancer. The light produced using these compositions with varyingamounts of the enhancer led to intense emission which could be imagedfor at least 2 weeks.

Surprisingly it has been found that compositions containing 0.5 mg/mL ofEnhancer A produced light emission whose intensity was nearly constantfor 4 days with no change in the relative band intensities. Lightemission produced on PVDF membranes persisted at useful levels for verylong periods of time, exceeding a month. The 5 pg band could still beimaged with only a 20 min exposure after 5 weeks. This duration ofemission at useful levels is without precedent.

Example 28 Western Blot using Nitrocellulose Membrane

A Western blot assay according to the procedures in Example 27 wasperformed using nitrocellulose membrane as the solid phase. Transferrinstandards in the range of 5000-30 pg were used. A detection reagentwhich permitted detection of all levels of protein comprised 0.2 M 22buffer, pH 9.6, 0.88 mM MgCl₂, 0.33 mM acridan phosphate 1 and 0.5 mg/mLof Enhancer A. Detection could be performed over several hours.

Example 29 Southern Blot Assay with Chemiluminescent Detection

The use of a composition of the present invention for thechemiluminescent detection of DNA on nitrocellulosse membranes by thetechnique of Southern blotting is demonstrated in the following example.

Avidin-AP conjugate was obtained from Cappel Products (Durham, N.C.).Bovine serum albumin (heat shocked) was purchased from Sigma ChemicalCo. (St. Louis, Mo.). Human genomic DNA and human transferrin receptorcDNA were from Clontech (Palo Alto, Calif.). Biotinylated lambdaDNA/HindIII fragments, biotin-7-dATP and the Nick Translation kit werefrom Life Technologies, restriction endonuclease HindIII was fromBoehringer-Mannheim (Indianapolis, IN), and nitrocellulose membrane fromSchleicher & Schuell Inc (Keene, N.H.). X-ray film was X-OMAT AR fromKodak (Rochester, N.Y.).

Human genomic DNA (19.5 μg) was cleaved with HindIII to completion anddivided into 13 μg and 6.5 μg portions. Restricted DNA was purified byphenol/chloroform extraction and ethanol precipitation. Purified DNA wasseparated by electrophoresis on 0.75% agarose gel with 40 mmol/LTris-acetate, 2 mmol/L EDTA, pH 8.0 as the elution buffer. Followingelectrophoresis, the gel was rinsed with water, equilibrated for 12 minwith 0.25 mol/L HCl, rinsed with water again, incubated in 0.5 mol/LNaOH, 1.5 mol/L NaCl for 15 min then in a fresh change of the samesolution for 30 min, rinsed with water, and incubated in three changesof 1 mol/L tris, 1.5 mol/L NaCl, pH 7.5 for 15 min each.

Nitrocellulose membrane was soaked sequentially with water for two minand 10×SSC for 30 min. DNA was transferred to the membrane by capillaryblotting overnight in 10×SSC. The membrane was washed by gentleagitation in 10×SSC for 10 min at room temperature and air-dried onWhatman 3MM blotting paper for 30 min and baked at 80° C. under vacuumfor 2 h.

The membrane was soaked in 6×SSPE (20×SSPE is 3 mol/L NaCl, 0.2 mol/LNaH₂PO₄, 20 mmol/L EDTA, pH 7.4) followed by prehybridization for 3 h at42° C. in pre-hybridization solution: 6×SSPE, 50% freshly deionizedformamide, filtered 5×Denhardt's solution (50×is 1% Ficoll 400, 1% PVP,1% BSA (initial fraction by heat shock)), filtered 1% SDS and 200 μg/mLsheared, denatured herring sperm DNA. The hybridization probe, humantransferrin receptor cDNA was labeled with biotin-7-dATP by nicktranslation according to the manufacturers instructions. Genomic DNA washybridized overnight at 42° C in 6×SSPE, 45% formamide, filtered5×Denhardt's, 1% SDS, 200 μg/mL herring sperm DNA with 300 μg/mLdenatured biotinylated probe. The biotinylated probe was denatured byboiling 4 min and cooling 10 min at 0° C. The membrane was washed twicewith 0.5×SSC, 0.4% SDS at 25° C. for 5 min, three times with 0.5×SSC,0.4% SDS at 55° C. for 10 min, once with 2×SSC at 25° C. for 5 min,twice with TBS (50 mmol/L Tris-HCl, pH 7.4, 0.15 mol/L NaCl) for 3 min.After the wash step, the membrane was blocked at 63° C. for 1 h infiltered 3% BSA, 100 mmol/L Tris-HCl, pH 7.4, 0.15 mol/L NaCl and washedin T-TBS (0.05% Tween 20 in TBS) for 1 min.

The blocked membrane was incubated with a 1:2000 dilution of avidin-APin T-TBS for 12 min followed by four fresh changes of T-TBS for 5, 10,15 and 20 min followed by a final wash with TBS for 5 min. Excess bufferwas drained off and blots soaked in the detection reagent described inExample 27 for 3 min. Excess reagent was drained off, and the blotsplaced between transparent sheets and exposed to X-ray film.

The single copy gene was detected at 10.5 and 5.2 kbp by soaking themembrane with detection reagent and exposure to x-ray film for varyinglengths of time. After an incubation period of 12 min, a bandcorresponding to the single copy gene in both fractions was visible witha 5 min exposure to film using a reagent of the present invention.Shorter incubation times also produced excellent images. Multipleexposures could be easily performed for a day.

Example 30 Effect of Lucigenin on the Chemiluminescence Profile

The higher light intensity afforded by the addition of lucigenin to thereaction of acridan phosphate 5 with AP is shown by the plots in FIG. 7.Reaction of 100 μL portions of a solution of 5 (0.66 mM) in 0.1 M trisbuffer, pH 8.8 containing 0.88 mM MgCl₂, with 8×10⁻¹⁶ mol of AP at 25°C. were conducted in the presence and absence of 6.4 μM lucigenin. FIG.7 shows the much higher light intensity resulting from incorporation oflucigenin into the solution.

Example 31 Chemiluminescent Detection of Alkaline Phosphatase withCompound 5

A highly effective reagent composition for chemiluminescent detection ofalkaline phosphatase comprised 0.1 M tris buffer, pH 8.8, 6.4 μMlucigenin, 0.66 mM compound 5, 1 mg/mL SDS, 0.01 mg/mL Na₂SO₃, 0.033%(w/v) TWEEN 20 and 0.88 mM MgCl₂. Reaction of 100 μL of this compositionwith 8×10⁻¹⁶ mol of AP at 25° C. produced chemiluminescence whichreached maximum intensity in 2 min. FIG. 8 shows the comparison with areagent composition containing 5 and the cationic polymeric surfactantenhancer poly(vinylbenzyltributylphosphoniumchloride)-co-poly-(vinylbenzyltrioctylphosphonium chloride),containingabout a 3:1 ratio of tributyl:trioctyl groups (0.25TB/TO), triggered at37° C. Compositions containing the latter polymeric surfactant werefound previously to be the highest levels of chemiluminescence in theabsence of a CAC.

Example 32 Linearity and Sensitivity of Detection of AlkalinePhosphatase

The sensitivity and linearity of detection of AP was determined using areagent composition containing compound 5 and lucigenin (reagent A) andcompared to the results achievable using a reagent compositioncontaining compound 5 and 0.25TB/TO (reagent B). The reagents have thefollowing composition:

Reagent A Reagent B Compound 5, 0.66 mM Compound 5, 0.66 mM 0.1 M trisbuffer, pH 8.8 0.2 M 221 buffer, pH 9.6 0.01 or 0.88 mM MgCl₂ 0.88 mMMgCl₂ lucigenin, 6.4 μM 0.25 TB/TO, 0.5 mg/mL SDS, 1 mg/mL Na₂SO₃, 0.01mg/mL TWEEN 20, 0.033% (w/v)

To each of 3 wells in a 96-well white microplate, 10 μL dilutions of APcontaining between 8×10⁻¹³ mol and 8×10⁻²² mol of enzyme were added 100μL aliquots of detection reagent A or B. Light intensities were measuredafter 2.5 min. FIG. 9 shows the linear detection of alkalinephosphatase. The calculated detection limit (two standard deviationsover the background) was determined to be 3.5×10⁻²¹ mol for reagent Aand 1.2×10⁻¹⁹ mol for reagent B.

Example 33 Chemiluminescent Detection with Compounds 1-13

In the manner of Example 30, compositions containing 0.66 mM of each ofcompounds 1-13 with 0 and 6.4 μM lucigenin were reacted with 8×10⁻¹⁶moles of AP at 25° C. Each demonstrated significantly more intensechemiluminescence when lucigenin was in the reaction solution.

Example 34 Linearity and Sensitivity of Detection of AP using Compounds7-12

In the manner of Example 32, reagents were prepared according to thecomposition of reagent A substituting 0.66 mM of each of compounds 7-12in place of compound 5. To 100 μL portions of each of these reagents wasadded 10 μL dilutions of AP containing between 8×10⁻¹⁶ mol and 8×10⁻²²mol of enzyme or 10 μL of water for the reagent blank. In each case, thereaction solution containing 8×10⁻²¹ mol of enzyme produced a peaksignal within about 2 minutes which was higher than the blank. FIGS. 10and 11 and 18 depict the results for compounds 7, 8, and 12respectively.

Example 35 Time profile of Chemiluminescence using Compound 7

The rapid generation of chemiluminescence emitted by a reagentcomposition containing compound 7 is demonstrated in the followingexperiment. A 100 μL portion of a reagent consisting of 0.1 M trisbuffer, pH 8,8, 6.4 μM lucigenin, 0.66 mM acridan phosphate 7), 1 mg/mLsodium dodecyl sulfate, 0.01 mg/mL Na₂SO⁻³, 0.033% (w/v) TWEEN 20 and0.88 mM MgCl₂ was reacted with 8×10⁻¹⁶ mol of AP at room temperature.The chemiluminescence intensity reached a stable plateau in under 5 secas shown in FIG. 12.

Example 36 Increase in Chemiluminescence Intensity with Various CACs

Test solutions were prepared containing 21 mM of CAC 1-11 in DMSO. Thesewere diluted 1:1000 into a solution of acridan phosphate compound 5 in0.1 M tris buffer, pH 8.8 containing 0.88 mM MgCl₂. Triplicate 100 μLportions of each of the final reagent compositions were reacted with4×10⁻¹⁶ mol of AP at room temperature in a white microwell plate. Table5 shows the effect on plateau intensity (S), measured at 36 min andsignal/background (S/B) for each CAC. Each produced higher peak signal Sand S/B than a control without CAC.

TABLE 5 CAC S at 36 min 1 2602 2 45.3 3 5963 4 4645 5 34.7 6 72.3 7 61.68 19.1 9 781 10 21.1 11 9.3 None 2.8 1: Lucigenin 2: Basic Red 29 3:Basic Blue 66 4: Basic Blue 41 5: 3,3′-Diethylthiadicarbocyanine iodide6: 3,3′-Diethyl-9-methylthiacarbocyanine iodide 7:3,3′-Diethylselenacarbocyanine iodide 8: 3,3′-Diethylthiacyanine iodide9: IR-1040 10:5-[3-Ethoxy-4-(3-ethyl-5-methyl-2(3H)-benzothiazolyl-idene)-2-butenylidene]-3-ethyl-2-[(3-ethyl-4,5-diphenyl-2(3H)-thiazolylidene)methyl]-4,5-dihydro-4-oxothiazoliumiodide 11: IR-786 perchlorate

Example 37 Effect of Concentration of CAC on Chemiluminescent Reactionof 5 with AP

Chemiluminescent detection of AP with compositions of the presentinvention can be performed over a broad range of concentration of CAC.Compositions containing 0.66 mM compound 5 in 0.1 M tris buffer, pH 8.8containing 0.88 mM MgCl₂ were prepared with varying concentrations oflucigenin ranging from 6.4 mM to 6.4 nM by 10-fold serial dilutions of astock lucigenin solution. The control contained no lucigenin. Testsolutions (100 μL, 5 replicates) containing between 6.4 mM and 6.4 nMreacted with 4×10⁻¹⁶ mol of AP produced a higher signal (S) than thecontrol after a 3.5 min incubation at room temperature.

Example 38 Effect of Concentration of Anionic Surfactant onChemiluminescent Reaction of 5 with AP

Chemiluminescent detection of AP with compositions of the presentinvention can be performed over a broad range of concentration of theanionic surfactant SDS. Compositions containing 0.66 mM compound 5 and0.88 mM MgCl₂ in 0.1 M tris buffer, pH 8.8 with varying concentrationsof SDS ranging from 10 mg/mL to 10 μg/mL were prepared. The controlcontained no SDS. Test solutions (100 μL, 5 replicates) reacted with4×10⁻¹⁶ mol of AP produced a faster rise to peak signal at roomtemperature than the control.

Example 39 Effect of Concentration of Nonionic Surfactant onChemiluminescent Reaction of 5 with AP

Chemiluminescent detection of AP with compositions of the presentinvention can be performed over a broad range of concentration of thenon-ionic surfactant TWEEN 20. Compositions according to Reagent A inExample 32 were prepared but with 21 μM lucigenin and varyingconcentrations of the non-ionic surfactant ranging from 1.0% to 0.001%and lacking the Na₂SO₃. The control contained no non-ionic surfactant.The test solutions (100 μL, 5 replicates) and the controls were reactedwith 4×10⁻¹⁶ mol of AP at room temperature. Each test solution waseffective in extending the duration of chemiluminescence at or nearmaximum intensity.

Example 40 Effect of Concentration of Sodium Sulfite on ChemiluminescentReaction of 5 with AP

Chemiluminescent detection of AP with compositions of the presentinvention can be performed over a broad range of concentration of sodiumsulfite (Na₂SO₃). Compositions according to Reagent A in Example 32 wereprepared but with varying concentrations of Na₂SO₃ ranging from 1.0mg/mL to 1.0 μg/mL. The control contained no Na₂SO₃. Each test solution(100 μL, 5 replicates) produced a lower background signal (B) in theabsence of AP and a higher signal (S) than the control when reacted with4×10⁻¹⁶ mol of AP after a 3.5 min incubation at room temperature. Inthis experiment, the maximum signal was obtained using 1.0 μg/mL whilethe maximum S/B was obtained using 1.0 mg/mL.

Example 41 Western Blot Assay

A composition of the present invention were used to detect and quantifya protein, human transferrin in a Western blot with an AP-labeledantibody on a polyvinylidene difluoride (PVDF) membrane. Dilutions oftransferrin containing from 5000, 1000, 180, 30 and 5 pg, respectively,of protein were electrophoresed and transferred to PVDF membranes(Millipore, Bedford, Mass.). The transferrin bands were blocked with andthen reacted sequentially with goat anti-human transferrin and rabbitanti-goat-AP conjugate. The membranes were soaked briefly with reagentscomprising 0.1 M tris buffer, pH 8.8 containing 0.88 mM MgCl₂, 0.66 mMcompound 5 and 64 μM lucigenin. The membranes were placed betweentransparent plastic sheets and exposed to X-ray film. The bands forhuman transferrin were detected after 10 min with a 2.5 min exposure.The light produced using this composition led to intense emission whichcould be imaged for several hours.

Similar results were obtained using nitrocellulose blotting membraneinstead of PVDF membrane.

Example 42 Southern Blot Assay

A representative example of the use of a reagent of the presentinvention in a Southern blot assay is demonstrated in the followingexample.

Avidin-AP conjugate was obtained from Cappel Products (Durham, N.C.).Bovine serum albumin (heat shocked) was purchased from Sigma ChemicalCo. (St. Louis, Mo.). Mouse genomic DNA was from Clontech (Palo Alto,Calif.). Biotinylated lambda DNA/HindIII fragments, biotin-7-dATP andthe Nick Translation kit were from Life Technologies, restrictionendonuclease EcoRI was from Boehringer-Mannheim (Indianapolis, Ind.),and nylon membrane from Micron Separations Inc (Westborough, Mass.).X-ray film was X-OMAT AR from Kodak (Rochester, N.Y.).

Mouse genomic DNA (30 μg) was cleaved with EcoRI to completion. Two andfour μg portions were purified by phenol/chloroform extraction andethanol precipitation. Purified DNA was separated by electrophoresis on0.75% agarose gel with 40 mmol/L Tris-acetate, 2 mmol/L EDTA, pH 8.0 asthe elution buffer. Following electrophoresis, the gel was rinsed withwater, equilibrated for 12 min with 0.25 mol/L HCl, rinsed with wateragain, incubated in 0.5 mol/L NaOH, 1.5 mol/L NaCl for 15 min then in afresh change of the same solution for 30 min, rinsed with water, andincubated in three changes of 1 mol/L tris, 1.5 mol/L NaCl, pH 7.5 for15 min each.

Nylon membrane was soaked sequentially with water for two min and 10×SSCfor 30 min. DNA was transferred to the membrane by capillary blottingovernight in 10×SSC. The membrane was washed by gentle agitation in10×SSC for 10 min at room temperature and air-dried on Whatman 3MMblotting paper for 30 min and baked at 80° C. under vacuum for 2 h.

The membrane was soaked in 6×SSPE (20×SSPE is 3 mol/L NaCl, 0.2 mol/LNaH₂PO₄, 20 mmol/L EDTA, pH 7.4) followed by prehybridization for 3 h at42° C. in pre-hybridization solution: 6×SSPE, 50% freshly deionizedformamide, filtered 5×Denhardt's solution (50× is 1% Ficoll 400, 1% PVP,1% BSA (initial fraction by heat shock)), filtered 1% SDS and 200 μg/mLsheared, denatured herring sperm DNA. The hybridization probe, oncogeneprobe v-mos DNA (PanVera Corp., Madison, Wis.) was labeled withbiotin-7-dATP by nick translation according to the manufacturersinstructions. Genomic DNA was hybridized overnight at 42° C. in 6×SSPE,45% formamide, filtered 5×Denhardt's, 1% SDS, 200 μg/mL herring spermDNA with 500 ng of denatured biotinylated probe. The biotinylated probewas denatured by boiling 4 min and cooling 10 min at 0° C. The membranewas washed twice with 0.5×SSC, 0.4% SDS at 25° C. for 15 and 35 minrespectively, three times with 0.5×SSC, 0.4% SDS at 50° C. for 10 min,once with 2×SSC at 25° C. for 5 min, twice with TBS (50 mmol/L Tris-HCl,pH 7.4, 0.15 mol/L NaCl) for 3 min. After the wash step, the membranewas blocked at 65° C. for 1 h in filtered 3% BSA, 100 mmol/L Tris-HCl,pH 7.4, 0.15 mol/L NaCl and washed in T-TBS (0.05% Tween 20 in TBS) for1 min.

The blocked membrane was incubated with a 1:2000 dilution of avidin-APin T-TBS for 12 min followed by four fresh changes of T-TBS for 5, 10,15 and 20 min followed by a final wash with TBS for 5 min. Excess bufferwas drained off and blots soaked in either the detection reagentdescribed in Example 41 for 4 min. Excess reagent was drained off, andthe blots placed between transparent sheets and exposed to X-ray film.

The single copy gene was detected at 14.5 kbp by soaking the membranewith detection reagent and exposure to x-ray film for varying lengths oftime. After an incubation period of 9 min, a band corresponding to thesingle copy gene in both fractions was visible with a 5 min exposure tofilm. Multiple exposures could be performed for a day by using longerexposures.

Example 43 Chemiluminescent Immunoassay of hCG

A method for detection of hCG by chemiluminescent immunoassay wasperformed on the IMMULITE Automated Analyzer using an IMMULITE kitsupplied by Diagnostic Products Corp. (Los Angeles, Calif.) according tothe protocol provided by the manufacturer. Reagent A of Example 32 wassubstituted for the detection reagent supplied in the kit. The softwarewas modified to allow a shorter substrate incubation. All data pointsare the average of triplicate tests except for blank readings which werethe average of 5 tests of the sample diluent. Analytes were prepared byserial dilution of special calibrators with the standard diluentssupplied in the kit. Chemiluminescence measurements were made at 1.5minutes after substrate introduction.

A minor modification of the injection mechanism was made to minimize thedead volume of chemiluminescent reagent in the tubing. The substrateheater was disconnected and an 18″×{fraction (1/16)}″ OD clear teflontubing wrapped in black electrical tape having flared ends was connecteddirectly between the substrate pump and the gray substrate dispensingnozzle. A similar length of the same teflon tubing was attached to theinlet port of the substrate pump. This inlet tubing was placed in thebottle containing the substrate. No attempt was made to preheat ortemperature control the substrate. Insensitivity to temperature isindicated by the tight CV's even in the absence of external substratetemperature control.

Independent tests on rapid reading luminometers indicate that thesubstrate can be read with as little as 10 seconds incubation timeyielding no loss of sensitivity or accuracy. Assay results as shown inFIG. 13 and Table 6 demonstrate the utility of the present compositionsin a sandwich-type immunoassay.

TABLE 6 IMMULITE hCG Assay Tabulated Data mIU/mL hCG Intensity (CPS) %CV 6675 47332040 3.8 3000 29174720 1.2 1000 11031867 1.5 300 2906560 2.5100 977760 2.6 30 288883 0.7 10 133573 6.3 3 71507 5.9 1 54738 7.4 Blank47634 9.0

Example 44 Rapid Chemiluminescent Immunoassay of TSH

A method for detection of TSH by chemiluminescent immunoassay wasperformed on the IMMULITE Automated Analyzer using an IMMULITE RTH RapidTSH Assay kit from Diagnostic Products Corp. according to themanufacturer's protocol with modifications as described in Example 43.Reagent A of Example 32 was substituted for the detection reagentsupplied in the kit.

The reagent background was tested by removing the antibody conjugatesfrom a Third Generation TSH test wedge, carefully washing the wedge andreplacing the contents with Type 1 water. The observed substratebackground was approximately 5000 counts per second. This indicates thatthe non-specific binding background is several times the reagentbackground. Therefore, it is possible that reoptimization of thebiochemistry in the wedge could significantly extend the sensitivity ofseveral of the assays and/or allow a reduction of the biochemicalincubation time. Chemiluminescence measurements were made at 1.5 minutesafter substrate introduction.

TABLE 7 IMMULITE RTH Rapid TSH Assay Data μIU/mL TSH Intensity (CPS) %CV 75 17370000 0.9 10 2263413 5.3 1 202120 2.6 0.3 72357 2.6 0.1 368871.5 0.03 25607 2.6 0.01 22647 5.0 Blank 20810 2.0 Assay results as shownin FIG. 14 and Table 7 demonstrate the utility of the presentcompositions in providing a rapid assay.

Example 45 Chemiluminescent Immunoassay of TSH

A method for detection of TSH by chemiluminescent immunoassay wasperformed on the IMMULITE Automated Analyzer using an IMMULITE TSH ThirdGeneration TSH Assay kit from Diagnostic Products Corp. according to themanufacturer's protocol with modifications as described in Example 43.Reagent A of Example 32 was substituted for the detection reagentsupplied in the kit. Chemiluminescence measurements were made at 1.5minutes after substrate introduction.

TABLE 8 IMMULITE Third Generation TSH Assay Data μIU/mL TSH Intensity(CPS) % CV 75 25249293 1.6 10 4265600 1.5 1 415363 0.8 0.3 122580 4.30.1 54070 0.3 0.03 23810 3.7 0.01 17240 0.4 0.003 13900 1.7 Blank 129964.4 The assay results as shown in FIG. 15 and Table 8 demonstrate theutility of the present compositions in providing a highly sensitiveassay.

Example 46 Chemiluminescent Immunoassay of Estradiol

A method for detection of estradiol by chemiluminescent immunoassay wasperformed on the IMMULITE Automated Analyzer using a kit supplied byDiagnostic Products Corp. according to the manufacturer's protocol withmodifications as described in Example 43. Reagent A of Example 32 wassubstituted for the detection reagent supplied in the kit.Chemiluminescence measurements were made at 1.5 minutes after substrateintroduction.

TABLE 9 IMMULITE E2 Estradiol Assay Data pg/mL Estradiol Intensity (CPS)% CV 2000 500300 4.1 1000 783877 3.3 300 2521788 2.7 100 5398650 2.9 308808133 1.8 10 10036147 2.1 Blank 10536776 3.9 The assay results asshown in FIG. 16 and Table 9 demonstrate the utility of the presentcompositions in competitive-type immunoassays.

Example 47 Chemiluminescent Detection of Acid Phosphatase (AcP)

Reagent A of Example 32 was used in an experiment to detect acidphosphatase. Reaction of 100 μL of this composition with AcP (Sigma AcPLIN-TROL, reconstituted to 2.0 mL, 83 U/L) at ambient temperature in atest tube housed in a Turner TD-20e luminometer producedchemiluminescence which reached maximum intensity within 2-5 sec anddecayed to zero within 10-15 sec.

Acid phosphatase could be measured in the presence of alkalinephosphatase by means of this detection reagent. Since thechemiluminescent signal induced by AcP decayed nearly completely withinseconds, measuring the stable light intensity after about 15-20 secallows discrimination of AP activity as shown in FIG. 17. This methodallowed the simultaneous quantitation of both AcP and AP activity in thesame sample in one experiment. AcP could be easily measured in humanwhole blood.

Example 48 Linearity and Sensitivity of Detection of AP using Compound13

In the manner of Example 32, a reagents was prepared according to thecomposition below. To 100 μL portions of each of the reagent was added10 μL dilutions of AP containing between 8×10⁻¹⁶ mol and 8×10⁻²² mol ofenzyme or 10 μL of water for the reagent blank. Light intensity wasmeasured at 75 sec. FIG. 19 depicts the results.

Reagent Compound 13, 0.33 mM 0.1 M tris buffer, pH 8.8 MgCl₂, 5 μMlucigenin, 3.2 μM SDS, 0.5 mg/mL Na₂SO₃, 5 μg/mL TWEEN 20, 0.15 mg/mL(w/v)

Example 49

The following compounds have also been synthesized and found to providechemiluminescence when reacted with AP:

wherein V is t-butyl, CH₃, OCH₃F, Cl, Br, I, COCH₃, CN and NO₂ as wellas compounds of the formula:

wherein U is p-I, p-CH, m-OCH₃, o-Cl, m-Cl, o-Br, m-Br, p-Br and p-NO₂as well as compounds of this formula having a 3,4-dichloro-,2,5-dichloro- and 2,6-dichlorophenyl group.

The foregoing description and examples are illustrative only and not tobe considered as restrictive. It is recognized that modifications of thespecific compounds and methods not specifically disclosed can be madewithout departing from the spirit and scope of the present invention.The scope of the invention is limited only by the appended claims.

What is claimed is:
 1. A method for detecting an analyte in a sample bya chemiluminescent assay procedure which comprises:

(a) reacting a phosphatase enzyme with at least one compound of formulaI to produce chemiluminescence for detecting the analyte, wherein in thecompound of formula I, Het is selected from the group consisting of:

wherein * indicates the point of attachment of an enol phosphate group,wherein Z is selected from the group consisting of O and S atoms,wherein R₆ is selected from the group consisting of alkyl, substitutedalkyl, aryl, substituted aryl and aralkyl groups, wherein each H isindependently selected from H and a cationic center and wherein n is anumber which satisfies electroneutrality; (b) detecting thechemiluminescence; and (c) relating the amount of the chemiluminescenceto the amount of the analyte.
 2. The method of claim 1 wherein theanalyte to be detected is the phosphatase enzyme.
 3. The method of claim1 wherein the analyte to be detected is an inhibitor of the phosphataseenzyme.
 4. The method of claim 1 further comprising reacting the analytein the sample with an analyte binding compound which specifically bindswith the analyte wherein the analyte-binding compound is labeled withalkaline phosphatase.
 5. The method of claim 4 wherein theanalyte-binding compound is selected from the group consisting ofantibodies, antigens, haptens and nucleic acids.
 6. The method of claim1 further comprising reacting the analyte in the sample with: (a) alabeled analyte binding compound comprising an analyte binding compoundwhich specifically binds with the analyte and at least one secondspecific binding substance; and (b) a phosphatase-labeled bindingpartner for the second specific binding substance.
 7. The method ofclaim 1 wherein the detection is performed on a membrane.
 8. The methodof claim 7 wherein the membrane is selected from the group consisting ofa nitrocellulose membrane, a polyvinylidene difluoride membrane and anylon membrane.
 9. The method of claim 1 further comprising providingthe compound of formula I in a reagent composition comprising, in anaqueous solution, the compound of formula I and a surfactant enhancer inan amount effective to enhance the chemiluminescence.
 10. The method ofclaim 9 wherein the surfactant enhancer is a copolymer of avinylbenzyltributylphosphonium salt and a vinylbenzyltrioctylphosphoniumsalt.
 11. The method of claim 1 further comprising: (a) reacting thecompound of formula I with the phosphatase enzyme in a buffer at a firstpH for a first period of time; (b) adding a strongly basic triggersolution to the buffer solution to raise the pH of the buffer to asecond pH for inducing the chemiluminescence; and (c) measuring thechemiluminescence.
 12. The method of claim 11 wherein the first pH is inthe range 5.0-9.51 wherein the pH of the trigger solution is greaterthan about 11 and the first period of time is from about 1 seconds toabout 10 minutes.
 13. The method of claim 11 wherein the basic triggersolution contains a surfactant enhancer.
 14. The method of claim 13wherein the enhancer is a copolymer of a vinylbenzyltributylphosphoniumsalt and a vinylbenzyltrioctylphosphonium salt.
 15. A reagentcomposition which produces chemiluminescence in the presence of aphosphatase enzyme which comprises in an aqueous solution: a) a compoundof formula I:

which reacts with the phosphatase enzyme wherein Het is selected fromthe group consisting of:

wherein * indicates the point of attachment of an enol phosphate group,wherein Z is selected from the group consisting of O and S atoms,wherein R₆ is selected from the group consisting of alkyl, substitutedalkyl, aryl, substituted aryl and aralkyl groups, wherein each M isindependently selected from H and a cationic center and wherein n is anumber which satisfies electroneutrality; and b) a cationic aromaticcompound in an amount effective to increase the chemiluminescencecompared to that generated in the absence of the cationic aromaticcompound.
 16. The composition of claim 15 wherein the cationic aromaticcompound is selected from the group consisting of cyanine dyes,carbocyanine dyes, azo dyes, acridinium derivatives, methylene blue,Nile Blue, IR-1040, lucigenin and paraquat dichloride.
 17. Thecomposition of claim 15 further comprising an anionic surfactant in anamount effective to increase the speed with which maximumchemiluminescence intensity is reached and a non-ionic surfactant in anamount effective to increase the amount of chemiluminescence.
 18. Thecomposition of claim 17 wherein the anionic surfactant is selected fromalkylsulfates containing at least 10 carbon atoms and alkylsulfonatescontaining at least 10 carbon atoms.
 19. The composition of claim 17wherein the non-ionic surfactant is selected from polyoxyethylenatedalkylphenols, polyoxyethylenated alcohols, polyoxyethylenated ethers andpolyoxyethylenated sorbitol esters.
 20. The composition of claim 17additionally comprising a sulfite salt in an amount effective to reducechemiluminescence produced by the composition in the absence of aphosphatase enzyme.
 21. The composition of claim 18 wherein the anionicsurfactant is sodium dodecyl sulfate.
 22. The composition of claim 20wherein the sulfite salt is sodium sulfite.
 23. A method for producingchemiluminescence which comprises reacting a phosphatase enzyme with a)at least one compound of formula I:

wherein Het is selected from the group consisting of:

wherein * indicates the point of attachment of an enol phosphate group,wherein Z is selected from the group consisting of O and S atoms,wherein R₆ is selected from the group consisting of alkyl, substitutedalkyl, aryl, substituted aryl and aralkyl groups, wherein each M isindependently selected from H and a cationic center and wherein n is anumber which satisfies electroneutrality; and b) a cationic aromaticcompound in an amount effective to increase the chemiluminescencecompared to that generated in the absence of the cationic aromaticcompound.
 24. The method of claim 23 wherein the phosphatase enzyme isselected from the group consisting of acterial alkaline phosphatase,mammalian alkaline phosphatase, plant acid phosphatase, mammalian acidphosphatase and alkaline phosphatase conjugates.
 25. The method of claim23 wherein the alkaline phosphatase conjugate comprises alkalinephosphatase linked to a biological molecule selected from the groupconsisting of haptens, antibodies, proteins, nucleic acids andoligonucleotides.
 26. The method of claim 23 further comprisingproviding the compound of formula I and the cationic aromatic compoundin a reagent composition which composition further comprises, in anaqueous solution, an anionic surfactant in an amount effective toincrease the speed with which maximum chemiluminescence intensity isreached and a non-ionic surfactant in an amount effective to increasethe chemiluminescence.
 27. A method for detecting acid phosphatase andalkaline phosphatase in a sample suspected of containing both acidphosphatase and alkaline phosphatase by a chemiluminescent assayprocedure which comprises: (a) reacting the sample with a reagentcomposition comprising at least one compound of formula I,

wherein in the compound of formula I, Het is selected from the groupconsisting of:

wherein * indicates the point of attachment of an enol phosphate group,wherein Z is selected from the group consisting of O and S atoms,wherein R₆ is selected from the group consisting of alkyl, substitutedalkyl, aryl, substituted aryl and aralkyl groups, wherein each M isindependently selected from H and a cationic center and wherein n is anumber which satisfies electroneutrality, a cationic aromatic compound,an anionic surfactant in an amount effective to increase the speed withwhich maximum chemiluminescence intensity is reached and a non-ionicsurfactant in an amount effective to increase the chemiluminescence; (b)detecting the amount or intensity of chemiluminescence during an initialperiod; (c) waiting a second period of time until the chemiluminescencehas achieved a constant level; (d) detecting the amount or intensity ofchemiluminescence during a third period; (e) relating thechemiluminescence in the initial time period to the amount of acidphosphatase; and (f) relating the chemiluminescence in the third timeperiod to the amount of alkaline phosphatase.
 28. A process for thepreparation of a compound of formula I:

wherein Het is selected from the group consisting of:

wherein * indicates the point of attachment of an enol phosphate group,wherein Z is selected from the group consisting of O and S atoms,wherein R₆ is selected from the group consisting of alkyl, substitutedalkyl, aryl, substituted aryl and aralkyl groups, wherein each M isindependently selected from H and a cationic center and wherein n is anumber which satisfies electroneutrality comprising the steps of: (a)reacting a heterocyclic ester or thioester compound VIII having theformula:

wherein Het, Z and are as defined for compound I with a base to form anenolate of VIII; (b) reacting the enolate with a phosphorylating agentto form a protected enol phosphate TX having the formula:

wherein Het, Z and R₆ are as defined above and Y is a protecting group;and (c) deprotecting the enol phosphate to form the enol phosphate saltcompound I by reacting IX with at least one deprotecting agent in thepresence of a cationic species M if the cationic species is not a partof the deprotecting agent.
 29. The process of claim 28 wherein the stepof reacting the enolate of compound VIII with a phosphorylating agent toform a protected enol phosphate IX comprises the steps of: (a) reactingthe enolate of compound VIII with a phosphorus oxyhalide compound POW₃,where W is a halogen atom selected from F, Cl, Br and I to form an enoldihalophosphate X having the formula

wherein Het, Z and R₆ are as defined in compound VIII; and (b) reactingcompound X with at least two equivalents of a hydroxylic compound Y—OHto form the protected enol phosphate IX.
 30. The process of claim 28wherein the step of reacting the enolate of compound VIII with aphosphorylating agent to form a protected enol phosphate IX comprisesreacting the enolate of compound VIII with a phosphorylating agentcontaining the protecting groups Y and having the formula W—PO(OY)₂ andwherein W is a halogen atom selected from F, Cl, Br and I.
 31. Theprocess of claim 28 wherein the groups Y are selected from the groupconsisting of lower alkyl groups, substituted lower alkyl groups,phenyl, substituted phenyl and benzyl groups.
 32. The process of claim28 wherein the groups Y are connected to form the single group —CH₂CH₂—.33. The process of claim 28 wherein the deprotecting agent is selectedfrom the group consisting of organic and inorganic bases such as sodiumhydroxide, potassium hydroxide, potassium carbonate, sodium methoxide,sodium ethoxide, potassium t-butoxide, ammonium hydroxide, nucleophilicagents such as cyanide ion, fluoride ion.
 34. The process of claim 28wherein Y is a CH₂CH₂CN group and the deprotecting agent is selectedfrom sodium hydroxide and sodium carbonate.
 35. The process of claim 29wherein Y is a CH₂CH₂CN group and the deprotecting agent is selectedfrom sodium hydroxide and sodium carbonate.
 36. The method of claim 1wherein the phosphatase enzyme is selected from the group consisting ofbacterial alkaline phosphatase, mammalian alkaline phosphatase, plantacid phosphatase, mammalian acid phosphatase and alkaline phosphataseconjugates.
 37. The method of claim 1 wherein M is selected from H,alkali metal ions, alkaline earth ions, quaternary ammonium ions andquaternary phosphonium ions.
 38. The method of claim 1 wherein thecompound of formula I is reacted with the phosphatase enzyme in thepresence of a cationic aromatic compound.
 39. The method of claimwherein the cationic aromatic compound is selected from the groupconsisting of cyanine dyes, carbocyanine dyes, azo dyes, acridiniumderivatives, methylene blue, Nile Blue, IR-1040, lucigenin and paraquatdichloride.
 40. The method of claim 38 further comprising providing thecompound of formula I and the cationic aromatic compound in a reagentcomposition which composition further comprises, in an aqueous solution,an anionic surfactant in an amount effective to increase the speed withwhich maximum chemiluminescence intensity is reached and a non-ionicsurfactant in an amount effective to increase the chemiluminescence. 41.The composition of claim 15 wherein M is selected from H, alkali metalions, alkaline earth ions, quaternary ammonium ions and quaternaryphosphonium ions.
 42. The method of claim 23 wherein M is selected fromH, alkali metal ions, alkaline earth ions, quaternary ammonium ions andquaternary phosphonium ions.